A proportion is an expression which states that the two ratios are equal.

If two ratios are equal, we say that they are in proportion and use the symbol ‘::’ or ‘=’ to equate the two ratios

**Example: **3, 4, 9 and 12 are in proportion and is expressed as:

3 : 4 = 9 : 12 or 3 : 4 :: 9 : 12

__Demonstration__**:**

Are 30, 40, 45 and 60 in proportion?

**Solution:**

Ratio of 30 to 40 = 30: 40 = 3 : 4.

Ratio of 45 to 60 = 45: 60 = 3 : 4.

Since, 30 : 40 = 45 : 60. T

herefore, 30, 40, 45, 60 are in proportion.