If the store sells the dress for 40% off, that means it is worth 60% of its original price. 

$\displaystyle 100 - 40 = 60$

Therefore, if you multiply 60% times the original price of the dress, you will know what the current price of the dress is.

To do this, first divide your percentage by 100.

$\displaystyle 60\div100 = 0.6$

Then, multiply the result of this times the original price of the dress. 

$\displaystyle 80 \times 0.6 = 48$

The new result is your answer.

We can use ratios and proportions to solve this problem. Percentages can be written as ratios. The word “percent” means for every hundred. In the problem, we are told that $\displaystyle 60\%$ of the cars are red. In other words, for every hundred cars $\displaystyle 60$ of them are red. We can write the following ratio:

$\displaystyle 60:100\rightarrow\frac{60}{100}$

Reduce.

$\displaystyle \frac{60}{100}\rightarrow \frac{6}{10}\rightarrow \frac{3}{5}$

We know that there are $\displaystyle 100$ cars in the parking lot. We can write the following ratio by substituting the variable $\displaystyle Red$ for the number of red cars:

$\displaystyle Red:100\rightarrow \frac{Red}{100}$

Now, we can create a proportion using our two ratios.

$\displaystyle \frac{3}{5}=\frac{Red}{100}$

Cross multiply and solve for $\displaystyle Red$.

$\displaystyle 5 \times Red=3\times100$

Simplify.

$\displaystyle 5 Red=300$

Divide both sides of the equation by $\displaystyle 5$.

$\displaystyle \frac{5Red}{5}=\frac{300}{5}$

Solve.

$\displaystyle Red=60$

There are $\displaystyle 60$ red cars in the parking lot.

We can use ratios and proportions to solve this problem. Percentages can be written as ratios. The word “percent” means for every hundred. In the problem, we are told that $\displaystyle 10\%$ of the cars are red. In other words, for every hundred cars $\displaystyle 10$ of them are red. We can write the following ratio:

$\displaystyle 10:100\rightarrow\frac{10}{100}$

Reduce.

$\displaystyle \frac{10}{100}\rightarrow \frac{1}{10}$

We know that there are $\displaystyle 250$ cars in the parking lot. We can write the following ratio by substituting the variable $\displaystyle Red$ for the number of red cars:

$\displaystyle Red:250\rightarrow \frac{Red}{250}$

Now, we can create a proportion using our two ratios.

$\displaystyle \frac{1}{10}=\frac{Red}{250}$

Cross multiply and solve for $\displaystyle Red$.

$\displaystyle 10 \times Red=1\times 250$

Simplify.

$\displaystyle 10 Red=250$

Divide both sides of the equation by $\displaystyle 10$.

$\displaystyle \frac{10Red}{10}=\frac{250}{10}$

Solve.

$\displaystyle Red=25$

There are $\displaystyle 25$ red cars in the parking lot.

We can use ratios and proportions to solve this problem. Percentages can be written as ratios. The word “percent” means for every hundred. In the problem, we are told that $\displaystyle 25\%$ of the cars are red. In other words, for every hundred cars $\displaystyle 25$ of them are red. We can write the following ratio:

$\displaystyle 25:100\rightarrow\frac{25}{100}$

Reduce.

$\displaystyle \frac{25}{100}\rightarrow \frac{1}{4}$

We know that there are $\displaystyle 136$ cars in the parking lot. We can write the following ratio by substituting the variable $\displaystyle Red$ for the number of red cars:

$\displaystyle Red:136\rightarrow \frac{Red}{136}$

Now, we can create a proportion using our two ratios.

$\displaystyle \frac{1}{4}=\frac{Red}{136}$

Cross multiply and solve for $\displaystyle Red$.

$\displaystyle 4 \times Red=1\times136$

Simplify.

$\displaystyle 4 Red=136$

Divide both sides of the equation by $\displaystyle 4$.

$\displaystyle \frac{4Red}{4}=\frac{136}{4}$

Solve.

$\displaystyle Red=34$

There are $\displaystyle 34$ red cars in the parking lot.

We can use ratios and proportions to solve this problem. Percentages can be written as ratios. The word “percent” means for every hundred. In the problem, we are told that $\displaystyle 25\%$ of the cars are red. In other words, for every hundred cars $\displaystyle 25$ of them are red. We can write the following ratio:

$\displaystyle 25:100\rightarrow\frac{25}{100}$

Reduce.

$\displaystyle \frac{25}{100}\rightarrow \frac{1}{4}$

We know that there are $\displaystyle 164$ cars in the parking lot. We can write the following ratio by substituting the variable $\displaystyle Red$ for the number of red cars:

$\displaystyle Red:164\rightarrow \frac{Red}{164}$

Now, we can create a proportion using our two ratios.

$\displaystyle \frac{1}{4}=\frac{Red}{164}$

Cross multiply and solve for $\displaystyle Red$.

$\displaystyle 4 \times Red=1\times164$

Simplify.

$\displaystyle 4 Red=164$

Divide both sides of the equation by $\displaystyle 4$.

$\displaystyle \frac{4Red}{4}=\frac{164}{4}$

Solve.

$\displaystyle Red=41$

There are $\displaystyle 41$ red cars in the parking lot.

We can use ratios and proportions to solve this problem. Percentages can be written as ratios. The word “percent” means for every hundred. In the problem, we are told that $\displaystyle 60\%$ of the cars are red. In other words, for every hundred cars $\displaystyle 60$ of them are red. We can write the following ratio:

$\displaystyle 60:100\rightarrow\frac{60}{100}$

Reduce.

$\displaystyle \frac{60}{100}\rightarrow \frac{6}{10}\rightarrow \frac{3}{5}$

We know that there are $\displaystyle 135$ cars in the parking lot. We can write the following ratio by substituting the variable $\displaystyle Red$ for the number of red cars:

$\displaystyle Red:135\rightarrow \frac{Red}{135}$

Now, we can create a proportion using our two ratios.

$\displaystyle \frac{3}{5}=\frac{Red}{135}$

Cross multiply and solve for $\displaystyle Red$.

$\displaystyle 5 \times Red=3\times135$

Simplify.

$\displaystyle 5 Red=405$

Divide both sides of the equation by $\displaystyle 5$.

$\displaystyle \frac{5Red}{5}=\frac{405}{5}$

Solve.

$\displaystyle Red=81$

There are $\displaystyle 81$ red cars in the parking lot.

We can use ratios and proportions to solve this problem. Percentages can be written as ratios. The word “percent” means for every hundred. In the problem, we are told that $\displaystyle 40\%$ of the cars are red. In other words, for every hundred cars $\displaystyle 40$ of them are red. We can write the following ratio:

$\displaystyle 40:100\rightarrow\frac{40}{100}$

Reduce.

$\displaystyle \frac{40}{100}\rightarrow \frac{4}{10}\rightarrow \frac{2}{5}$

We know that there are $\displaystyle 400$ cars in the parking lot. We can write the following ratio by substituting the variable $\displaystyle Red$ for the number of red cars:

$\displaystyle Red:400\rightarrow \frac{Red}{400}$

Now, we can create a proportion using our two ratios.

$\displaystyle \frac{2}{5}=\frac{Red}{400}$

Cross multiply and solve for $\displaystyle Red$.

$\displaystyle 5 \times Red=2\times400$

Simplify.

$\displaystyle 5 Red=800$

Divide both sides of the equation by $\displaystyle 5$.

$\displaystyle \frac{5Red}{5}=\frac{800}{5}$

Solve.

$\displaystyle Red=160$

There are $\displaystyle 160$ red cars in the parking lot.

We can use ratios and proportions to solve this problem. Percentages can be written as ratios. The word “percent” means for every hundred. In the problem, we are told that $\displaystyle 50\%$ of the cars are red. In other words, for every hundred cars $\displaystyle 50$ of them are red. We can write the following ratio:

$\displaystyle 50:100\rightarrow\frac{50}{100}$

Reduce.

$\displaystyle \frac{50}{100}\rightarrow \frac{5}{10}\rightarrow \frac{1}{2}$

We know that there are $\displaystyle 200$ cars in the parking lot. We can write the following ratio by substituting the variable $\displaystyle Red$ for the number of red cars:

$\displaystyle Red:200\rightarrow \frac{Red}{200}$

Now, we can create a proportion using our two ratios.

$\displaystyle \frac{1}{2}=\frac{Red}{200}$

Cross multiply and solve for $\displaystyle Red$.

$\displaystyle 2 \times Red=1\times200$

Simplify.

$\displaystyle 2 Red=200$

Divide both sides of the equation by $\displaystyle 2$.

$\displaystyle \frac{2Red}{2}=\frac{200}{2}$

Solve.

$\displaystyle Red=100$

There are $\displaystyle 100$ red cars in the parking lot.

We can use ratios and proportions to solve this problem. Percentages can be written as ratios. The word “percent” means for every hundred. In the problem, we are told that $\displaystyle 30\%$ of the cars are red. In other words, for every hundred cars $\displaystyle 30$ of them are red. We can write the following ratio:

$\displaystyle 30:100\rightarrow\frac{30}{100}$

Reduce.

$\displaystyle \frac{30}{100}\rightarrow \frac{3}{10}$

We know that there are $\displaystyle 300$ cars in the parking lot. We can write the following ratio by substituting the variable $\displaystyle Red$ for the number of red cars:

$\displaystyle Red:300\rightarrow \frac{Red}{300}$

Now, we can create a proportion using our two ratios.

$\displaystyle \frac{3}{10}=\frac{Red}{300}$

Cross multiply and solve for $\displaystyle Red$.

$\displaystyle 10 \times Red=3\times300$

Simplify.

$\displaystyle 10 Red=900$

Divide both sides of the equation by $\displaystyle 10$.

$\displaystyle \frac{10Red}{10}=\frac{900}{10}$

Solve.

$\displaystyle Red=90$

There are $\displaystyle 90$ red cars in the parking lot.

We can use ratios and proportions to solve this problem. Percentages can be written as ratios. The word “percent” means for every hundred. In the problem, we are told that $\displaystyle 4\%$ of the cars are red. In other words, for every hundred cars $\displaystyle 4$ of them are red. We can write the following ratio:

$\displaystyle 4:100\rightarrow\frac{4}{100}$

Reduce.

$\displaystyle \frac{4}{100}\rightarrow \frac{2}{50}\rightarrow \frac{1}{25}$

We know that there are $\displaystyle 400$ cars in the parking lot. We can write the following ratio by substituting the variable $\displaystyle Red$ for the number of red cars:

$\displaystyle Red:40\rightarrow \frac{Red}{400}$

Now, we can create a proportion using our two ratios.

$\displaystyle \frac{1}{25}=\frac{Red}{400}$

Cross multiply and solve for $\displaystyle Red$.

$\displaystyle 25 \times Red=1\times400$

Simplify.

$\displaystyle 25 Red=400$

Divide both sides of the equation by $\displaystyle 25$.

$\displaystyle \frac{25Red}{25}=\frac{400}{25}$

Solve.

$\displaystyle Red=16$

There are $\displaystyle 16$ red cars in the parking lot.