Answer
$\displaystyle \frac{1}{3},\qquad x\neq 3$
Work Step by Step
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)
