Here's the series:
I took what I was given into the \(S_n = {a(1 - r^{n}) \over 1 - r}\) formula where:
\({S_n}\) is the sum of \({n}\) number of terms
\({a}\) is the first term
\({r}\) is the common ratio
Here's my work:
But I didn't get the answer, which is
I'm confused as to what did I do wrong?
