Answer
$-m^{2}n-5mn^{2}$
Work Step by Step
We are given the polynomial $6m^{2}n-8mn^{2}+3mn^{2}-7m^{2}n$.
We can use the distributive property to combine like terms.
$6m^{2}n-8mn^{2}+3mn^{2}-7m^{2}n=(6-7)m^{2}n+(-8+3)mn^{2}=(-1)m^{2}n+(-5)mn^{2}=-m^{2}n-5mn^{2}$