Answer
$9\frac{1}{3}mn-8m^2.$
Work Step by Step
By multiplying each term of the polynomial by the factor $\frac{2}{3}m$, and then adding the products, we have
$$
\frac{2}{3}m(14n - 12m)=\frac{2}{3}m(14n )+\frac{2}{3}m(- 12m)\\
=\frac{28}{3}mn-8m^2=9\frac{1}{3}mn-8m^2.
$$
