Understanding Ratios
A ratio compares two or more quantities, showing their relative sizes. For example, a ratio of 2:3 means for every 2 parts of the first item, there are 3 parts of the second item.
How to Simplify a Ratio
To simplify a ratio, find the Greatest Common Divisor (GCD) of all the numbers in the ratio. Then, divide every number by the GCD.
Example: 10 : 15
GCD is 5.
10 ÷ 5 = 2
15 ÷ 5 = 3
Simplified: 2 : 3
GCD is 5.
10 ÷ 5 = 2
15 ÷ 5 = 3
Simplified: 2 : 3
How to Find Missing Values
When you have an equivalent ratio, you can solve for a missing number using cross-multiplication.
Given: A : B = X : Y
To find X: (A × Y) ÷ B = X
To find Y: (B × X) ÷ A = Y
To find X: (A × Y) ÷ B = X
To find Y: (B × X) ÷ A = Y