1. McDonald’s sells 5 times as many coffees as Burger King. The difference in sales on Monday between the two was 20 cups. How many cups of coffee did each restaurant sell?

Answer 1

Hi Hannah. Since we don't know the number of cups for either Burger King or McDonald's we will use x for the unknown number.

We don't know anything about Burger King's sales so we can label Burger King as x. We do know that McDonald's sells 5 times as many coffees as Burger King so we can label McDonald's as 5x:

Burger King = x

McDonald's = 5x

The word difference in the "difference in sales between the two was 20 cups" means subtraction so we can write an equation as follows:

5x - x = 20

Next , we solve the equation by first combining like terms. This means we need to subtract the x's:

4x = 20

Finally, we solve for x by performing the opposite operation than what is shown in the problem. 4x means 4 multiplied by x, so we will divide both sides by 4 in order to isolate x or get it alone on one side of the equal sign:

4x = 20

4 4

x = 5

Now that we know the value of x we can solve the problem. If you remember, Burger King was labeled as x and McDonald's was labeled as 5x. Therefore:

Burger King = 5 cups of coffee sold on Monday

McDonald's = 5x = 5(5) = 25 cups of coffee sold on Monday

Answer 2

M=5B

M-B=20

5B-B = 20

4B = 20

B = 20/4 = 5

M=5B = 25

M= McDonalds

B= Burger King