To find the percent of change, you must divide the difference between the original and new amounts by the original amount. In this case, it would be \(\displaystyle \frac{50-40}{50}\), or \(\displaystyle \frac{10}{50}\), which is equivalent to 20%.

So the change in population is 9,000. The percentage of population loss is just the change in population divided by the original population.

\(\displaystyle x=\frac{9,000}{67,000}=0.134\)

Turn 0.134 into a percent so that we get 13.4%.  So the percent of population loss is 13.4%.

To find the percent decrease, we need to calculate the difference between the original (larger) amount of land and the final (smaller) amount. Here, this difference is \(\displaystyle 120-84=36\) acres. This value refers to the amount of decrease. We now need to convert it into a percent.

To do so, we use a proportion: \(\displaystyle \frac{36}{120} = \frac{x}{100}\).

Cross-multiplication shows us that \(\displaystyle x\) is equal to

 \(\displaystyle \frac{36}{120}\cdot 100\), so \(\displaystyle x=\frac{3}{10}(100)=30\) percent.

Write the formula to find percent decrease:

\(\displaystyle \textup{Percent Decrease}= \frac{\textup{Old-New}}{\textup{Old}} \times 100\%\)

Subsitute the values into the formula.

\(\displaystyle \frac{75.99-52.99}{75.99} \times 100\%= 30.267\)

The approximate percent decrease is \(\displaystyle 30\%\).

To find the percentage that the original price decreased, use the following relation:

\(\displaystyle \frac{original-new}{original}=\frac{25-15}{25}=.4\)

Now, to find the percentage, simply multiply the decimal by 100.

\(\displaystyle .4*100=40\)

If the amount of houses decreased by 85%, that means the amount that remain is 100% - 85%, or 15%. We want to find 15% of 70%. Since we're leaving our answer as a percentage, we can just leave 70% as 70, and convert 15% to 0.15 and multiply:

\(\displaystyle \small 70*0.15= 10.5\).

This means our answer is 10.5%.

To figure out the percent change, we want to figure out the amount that the population changed. We can do this by subtracting:

\(\displaystyle \small 501,662 - 390,113 = 111,549\)

Now we want to figure out what percent that change was of the original. In other words, 111,549 is what percent of 501,662. We can write that as a solvable equation knowing that "of" means multiply:

\(\displaystyle \small 111,549 = \frac{x}{100}*501,662\) divide both sides by 501,662

\(\displaystyle \small 0.222 \approx \frac{x}{100}\) multiply by 100 to convert this decimal into a percentage

\(\displaystyle \small 22.2 \% = x\)

To find the percent change of two numbers, you use the formula: 

\(\displaystyle \small \frac{difference}{original}\times 100\).

This formula in the context of this question: 

\(\displaystyle \small \small \frac{312-170}{312}\times100 = \frac{142}{312}\times 100 = \frac{71}{156}\times 100 \approx45.5\%\).

Thus, now know that if we subtract about forty six percent of the original number from the original number, we would get the second number. We have about a forty six percent decrease. 

To find the percent of decrease from one number to the next we use the formula: 

\(\displaystyle \small \frac{difference}{original}\times 100.\)

In this case, the difference is 

\(\displaystyle \small 38-24 = 14\).

So our formula would be 

\(\displaystyle \small \frac{14}{38}\times100 \approx 37\%\).

From \(\displaystyle \small 38\) to \(\displaystyle \small 24\) is about a \(\displaystyle \small 37\%\) decrease.