#### Answer

(a) $f^{-1}(7)=2$
(b) $f(-1)=3$

#### Work Step by Step

(a) We are given: $f(2)=7$. We know that the inverse of a one-to-one function has the $x$ and $y$ values switched, so: $f^{-1}(7)=2$.
(b) We are given: $f^{-1}(3)=-1$. We know that the inverse of a one-to-one function has the $x$ and $y$ values switched, so: $f(-1)=3$