# 7. Addition and Subtraction of Fractions

Recall that to **add** or **subtract** fractions, we
need to have the **same denominator.**

### Example 1

Add the fractions: `2/3+4/15`

**Solution: **Here, the **lowest common denominator** which we can use is
`15`. So we have:

`2/3+4/15=10/15+4/15=14/15`

**Subtraction** works in the same way, as we see in the next example.

### Example 2

`6/7-5/14`

### Example 3

`a/(6y)-(2b)/(3y^4)`

### Example 4

`(x-1)/(2x^3-4x^2)+5/(x-2)`

### Exercises

Simplify the following.

**(1)**** **`2/(s^2)+3/s`

**(2)**** **`5+(1-x)/2-(3+x)/4`

**(3)**** **`5/(6y+3)-a/(8y+4)`

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