Answer
$\frac{dy}{dt}=-4(1+3e^{-0.5t})^{-2} ( 3e^{-0.5t} ) (-0.5) $
Work Step by Step
$h(p)=\frac{4}{p}$; $p(t)=1+3e^{-0.5t}$
Composite function will be
$y=h(1+3e^{-0.5t})=\frac{4}{ 1+3e^{-0.5t} }=4(1+3e^{-0.5t}) ^{-1} $
Taking derivative with respect to t
$\frac{dy}{dt}=-4(1+3e^{-0.5t})^{-2} \frac{ d( 1+3e^{-0.5t}) }{dt}$
$\frac{dy}{dt}=-4(1+3e^{-0.5t})^{-2} 3e^{-0.5t} (-0.5) $
