## Intermediate Algebra (6th Edition)

We are given $\frac{3x}{x+3}+\frac{9}{x+3}$. Both denominators are the same, so we can combine the numerators over the common denominator. $\frac{3x}{x+3}+\frac{9}{x+3}=\frac{3x+9}{x+3}=\frac{3(x+3)}{x+3}=3$