Let the first term be $a$.  Because the sum of the series is $16$, we have $16= \frac{a}{1-(-1/5)} = \frac{a}{6/5} = \frac{5a}{6}$.  Therefore, $a=\frac{96}{5}$.
An infinite geometric series has common ratio $-1/5$ and sum $16.$  What is the first term of the series?