## 2.3. Ratio, proportion, and variation

### 2.3.1. Ratio

A ratio (:) is the relation between two like numbers. For example, the ratio 5:7 can be written as a fraction, 5/7, or as division 5 ÷ 7. We read the ratio 5:7 as 5 to 7 or 5 per 7.

A ratio can be expressed by a fraction $\left(\frac{a}{b}\right)$ or by a colon (:). So, the ratio of two numbers a and b can be written as a:b which is the same as the fraction $\frac{a}{b}$, where b ≠ 0.

##### Example 1

Reduce the ratio 20:35 to the lowest term.

##### Solution

20:35 = 4/7.

##### Example 2

Reduce the ratio ...

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