**Ratio:-**

A ratio is a mathematical expression of comparing two quantities by division.

It is written using ‘:’

**For ****Example:- **5: 2.

**Note: –** The unit must be same to compare two quantities

**Equivalent Ratios:-**

If we multiply or divide both the numerator and denominator to the same number then we find the equivalent ratio.

**For example:- ** **, , **

* *

**The Lowest form of the Ratio:-**

If there is no common factor of numerator and denominator except one then it is the lowest form of the ratio.

For eg – , , etc.

* *

**Proportion:-**

When we say that two ratios are equal then it is called Proportion.

** = **

It is written as a:b::b:c

**Unitary Method:-**

If we find the value of one unit then calculate the value of the required number of units this is called the Unitary method.

**For example:-**

If the cost of 4 books is 320 Rs. then what will be the cost of 8 books?

Cost of 3 books = Rs. 320

Cost of 1 book = = Rs. 80

Cost of 6 books = = Rs. 640