So i started calculus and am currently stuck at the following problem.

Q.Evaluate by algebraic techniques:

$\displaystyle \lim_{x\rightarrow a}\frac{x^{n}-a^{n}}{x^{m}-a^{m}}$

The answer provided by the book is:

$\displaystyle \frac{n}{m}x^{n-m}$

Thanks.