If two resistors with resistances $R_1$ and $R_2$ are connected in parallel, then the total resistance $R$, measured in ohms ($\Omega$), is given by
If $R_1$ and $R_2$ are increasing at rates of $0.3~\Omega/s$ and $0.2~ \Omega/s$, respectively, how fast is $R$ changing when $R_1 = 70~\Omega$ and $R_2 = 80~\Omega$? (Round your answer to three decimal places.)
I honestly don't even know where to start with this other than taking the derivative of the given equation, but I can't even do that. When I tried I couldn't get an answer. I really need some help!