## Precalculus (6th Edition) Blitzer

$\displaystyle \frac{1}{3},\qquad x\neq 3$
Complex rational expressions have rational expressions in the numerator or/and in the denominator. Here, the numerator contains $\displaystyle \frac{x}{3}$. Multiplying with 3 would get rid of it. $\displaystyle \frac{3}{3}\times\frac{\dfrac{x}{3}-1}{x-3}=\frac{x-3}{3(x-3)}$ ... The expression has a common factor. Reduce. $=\displaystyle \frac{1}{3},\qquad x\neq 3$ ($3$ is excluded as $(x-3)$ was a part of the expression before reducing)