How to Solve a proportion word problem in algebra

In this math lesson we will learn how to solve a proportion word problem. Watch the video to learn how to set up a proportion, solve it, and interpret the answer.

Definition

A proportion is a statement that two ratios (or fractions) are equal. The cross products of the terms in a proportion are equal.

15/20 = 12/16 is a proportion (the two ratios are 15/20 and 9/16)

To write the cross products, multiply the numerator of the first fraction with the denominator of the second one; and then the denominator of the first fraction with the numerator of the second one.

15 x 16 = 20 x 12

240 = 240 (true)

You can use proportions to solve all types of problems. Often, one of the terms in the proportion is unknown. To solve a proportion means to find the value of the unknown term, so that when you replace the variable with that value, you get a true statement.