Question

Brian’s family drinks a gallon of milk in 3 days. How much milk does his family drink in 5 days?


The proportion for this situation is
3 days
1 gallon
=
5 days
x gallons
. Which equation can you use to solve the problem?

5x = 3
15x = 1
5x = 1
3x = 5

Answer 1

\[\frac{ 3 }{ 1 }=\frac{ 5 }{ x }\]
(for simplicity's sake, I will temporarily "disregard" units since they're the same on both sides. let's just look at the numbers and variables.)

what do you get when you cross-multiply this equation?

Answer 2

if you need a refresher on cross multiplying, remember that you multiply in an X-shaped pattern, like this diagram illustrates: https://www.wikihow.com/images/thumb/c/cf/Cross-Multiply-Step-3-Version-3.jpg/v4-460px-Cross-Multiply-Step-3-Version-3.jpg.webp