Answer
$\displaystyle \frac{3n^{2}+4m}{mn^{2}}$
Work Step by Step
$(\displaystyle \frac{m}{3})^{-1}+(\frac{n}{2})^{-2}$=.........$(\displaystyle \frac{a}{b})^{m}=\frac{a^{m}}{b^{m}}$
$=\displaystyle \frac{m^{-1}}{3^{-1}}+\frac{n^{-2}}{2^{-2}}$=.........$\displaystyle \frac{1}{a^{n}}=a^{-n}$
$=\displaystyle \frac{3^{1}}{m^{1}}+\frac{2^{2}}{n^{2}}$
$=\displaystyle \frac{3}{m}+\frac{4}{n^{2}}$=........common denominator =$mn^{2}$ ........
$=\displaystyle \frac{3n^{2}}{mn^{2}}+\frac{4m}{mn^{2}}$
$=\displaystyle \frac{3n^{2}+4m}{mn^{2}}$
