To find the cost of the cheeseburger after the discount is applied we need to first find out how much 20% of 3.50 is.

$\displaystyle 3.50\cdot 0.20=0.70$

Thus the discount is 70 cents, or $\displaystyle \$ 0.70$.

Now to find the new price we will need to subtract the discount from the original amount.

$\displaystyle 3.50-0.70=2.80$

Therefore the price of the cheeseburger on Wednesday is $\displaystyle \$ 2.80$.

To find what percentage of her salary her bonus was we need to set up a proportion.

 $\displaystyle \frac{7,000}{70,000}=\frac{x}{100}$.

Now we cross multiply and divide to get our percentage.

$\displaystyle \frac{7,000\cdot 100}{70,000}=10\%$.

To find out how many slices of roast beef Jeff needs to buy in a week we first need to calculate how many slices of roast beef Sandy eats in a week.

We know that she eats 3 slices per day. Using this we can create a unit multiplier to find out how many slices she eats in a week. 

Since there are 7 days in a week the convertion becomes,

$\displaystyle \frac{3slices}{1day}\cdot \frac{7days}{1week}=\frac{3\cdot 7slices}{1 week}=\frac{21 slices}{1 week}$.

To find out how many times more the non-resident tuition is compared to the in state resident tuition we need to create a proportion.

First we will round out numbers $\displaystyle \$8,374$ is about $\displaystyle \$8,000$ and $\displaystyle \$33,624$ is about $\displaystyle \$32,000$.

Now we set up our fraction:

$\displaystyle \frac{32000}{8000}=\frac{32}{8}=4$.

To find the total number of games the baseball team won we need to add all of the games they won together.

$\displaystyle 88+1+3+4+4$

$\displaystyle =89+7+4$

$\displaystyle =100$

To find the percentage of eligible players that were drafted we need to create a proportion.

$\displaystyle \frac{drafted}{eligible}=\frac{x}{100}$

$\displaystyle \frac{60}{1200}=\frac{x}{100}$

Now we need to cross multiply and divide to solve the problem.

$\displaystyle \frac{60\cdot 100}{1200}=\frac{6000}{1200}=\frac{60}{12}=5\%$

To find the minimum numer of votes needed to win we can set up the following equation.

$\displaystyle \frac{1}{2}\cdot \text{votes}+1$

Since we know our number of votes is 538 we get,

$\displaystyle \frac{1\cdot 538}{2}+1$

$\displaystyle =269+1=270$

To find out how many donuts John can buy we first need to see how many dozens he can buy with his $18.

To find this we use the following fraction,

$\displaystyle \frac{\$18}{\$3}=6$.

From here we multiply each dozen by the number of donuts in a dozen which is 12.

$\displaystyle 6\cdot 12=72$.

Therefore, John can buy 72 donuts.

To find how many more people Country A has than B we need to subtract the number of people in Country B from that in Country A.

$\displaystyle 1.3 \text{ billion}-1 \text{ billion}=0.3\text{ billion}$

From here we will convert the units from billion to million.

0.3 billion is equivalent to 300,000,000

To find how much the athlete earned per game we need to set up a fraction.

$31.9 million is about $32,000,000 and 82 games rounds to 80.

So $\displaystyle \frac{32,000,000}{80}=400,000$.