Introduction to Related Rates Practice Test

A rectangle has length $x$ and width $y$ with $y=\dfrac{100}{x}$; when $x=20$ and $\dfrac{dx}{dt}=1$, what is $\dfrac{dy}{dt}$?

A cylinder has lateral area $L=2\pi rh$; at $r=2$, $h=9$, $\dfrac{dr}{dt}=1$, and $\dfrac{dh}{dt}=-2$, what is $\dfrac{dL}{dt}$?