Can someone show me how these two series are equal? Having a hard time with the algebra..

$\displaystyle\sum^{\infty}_{n=1}\dfrac{5^{n+1}}{3^{n-1}}=\displaystyle\sum^{\infty}_{n=1}\left(\dfrac{5^n}{3^n}\right)\left(\dfrac{5^1}{3^{-1}}\right)=\displaystyle\sum^{\infty}_{n=1}5\cdot3\left(\dfrac{5}{3}\right)^n=\displaystyle\sum^{\infty}_{n=1}15\left(\dfrac{5}{3}\right)^n$

:) Hope this helps