Suppose $g$ Is the Inverse Function of a Differentiable Function $f$ And $G ( x ) = \frac { 1 } { g ( x ) }$

Suppose $g$ is the inverse function of a differentiable function $f$ and $G ( x ) = \frac { 1 } { g ( x ) }$ .
If $f ( 4 ) = 3$ and $f ^ { t } ( 4 ) = \frac { 1 } { 16 }$ , find $G ^ {t} ( 3 )$ .