# Solving Proportions

A proportion is an equation stating that two ratios are equal (two equivalent fractions)

Finding the missing value in a proportion means finding the missing value for two equivalent fractions.

There are three ways to solve proportions

Method 1: Vertical

Since 2 x 3 = 6, then 10 x 3 = 30. So the missing value is 30.

Method 2: Horizontal

Since 2 x 5 = 10, then 6 x 5 = 30. So the missing value is 30.

Method 3: Cross-products

Cross multiply and solve for X.

The missing value is 30.

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Solving Proportions by Cross Multiplication

In an proportional relationship such as

we can multiply the numerator of each side by the denominator of the other side.

The cross products of a proportion are equal. This property help us solve for an unknown value.

Solving proportions worksheets with an unknown variable  (using only integers):

### PP19      Proportion_I10

Solving proportions worksheets with an unknown variable  (with one decimal):

### PP31      Proportion_D12

If one term of a proportion is not known, we can use cross multiplication to find its value.