Find whether the series diverges and its sum: $\sum_{n = 1}^\infty (-1)^{n+1} \frac{3}{5^n}.$
I found that the series converges using the Alternating Series test because the absolute value of each $n$ decreases while the value of $n$ increases. Then I took the limit as $x$ approaches infinity of $3/5^x$ which is $0$.
But I am not sure how to go about finding the sum at this point. This is a practice exam, so the solution is more important then the actual answer.