# Keith sold half of his comic books and then bought 9 more. He now has 15. How many did he begin with?

Dec 6, 2016

Keith had $12$ comic books to begin with.

#### Explanation:

If we represent the original number of comic books as $x$, we can write the following equation:

$\frac{x}{2} + 9 = 15$

Subtract $9$ from both sides.

$\frac{x}{2} = 6$

Multiply both sides by $2$.

$x = 12$