Nathan B. answered • 03/09/15

Tutor

5
(20)
Elementary and Algebraic skilled

Let's start by defining our variables:

p = popcorn

d = drinks

Here's what we know:

2p + 4d = 22

3p + 2d = 21

I look at that 2d and 4d and see an easy elimination. By multiplying the second equation by -2, we can eliminate the d and solve for p:

2p + 4d = 22

-6p - 4d = -42

-6p - 4d = -42

-4p = -20

Divide both sides by -4, and:

p = 5

So popcorn costs $5. Using that, we can solve for d:

2 * 5 + 4d = 22

10 + 4d = 22

4d = 12

d = 3

So small drinks are $3.

Let's check our answer by putting the values into the second problem:

3 * 5 + 2 * 3 = 21

15 + 6 = 21

21 = 21