When we simplify algebraic expressions** we combine the coefficients of like terms.**

**Like terms are **terms with matching letters.

3a, 4a and a are like terms.

2b, -b, -5b are like terms.

2b and b^{2} are not like terms.

3b and 3 are not like terms.

3b, 5c and -2 are not like terms.

**Example**

Simplify **-4 + 3b + 4b - a + 2b + 6a + 3
**

**Answer**

Look at the coefficients of all the **a**s...... -a + 6a which are -1a + 6a

Combine them to get -1 + 6 = 5

So we get **5a**

Look at the coefficients of all the **b**s...... 3b + 4b + 2b which are 3b + 4b +2b

Combine them to get 3 + 4 +2 = 9

So we get **9b**

Combine the numbers which are** **-4 + 3 =** -1**

The answer is **5a + 9b - 1**