Question

n²+3m²          3m-4n
-----------   -   ----------- =?
   mn                  n

Answer 1

$\displaystyle \frac{n^{2}+3m^{2}}{mn}- \frac{3m-4n}{n}= \frac{n^{2}+3m^{2}-m(3m-4n)}{mn}= \\ \\ = \frac{n^{2}+3m^{2}-3m^{2}+4mn}{mn}= \frac{n^{2}}{mn}+ \frac{4mn}{mn}= \frac{n}{m}+4$