Answer
$\frac{8}{15}$
Work Step by Step
We know that $a^{−n}=\frac{1}{a^{n}}$ (as long as a is a nonzero real number and n is an integer).
Therefore, $5^{-1}+3^{-1}=\frac{1}{5}+\frac{1}{3}=\frac{1\times3}{5\times3}+\frac{1\times5}{3\times5}=\frac{3}{15}+\frac{5}{15}=\frac{3+5}{15}=\frac{8}{15}$.
