We keep the -12 as it is. For the $m$ terms, we add the exponents because they are being multiplied, giving us $m^{4+3}=m^{7}$. For the $n$ terms, we also add the exponents, giving us $n^{8+2}=n^{10}$. So, the expression becomes:
$$
\frac{-12 m^{7} n^{10}}{36
Show more…