Answer
$-10m^5n^3$
Work Step by Step
RECALL:
$a^m \cdot a^n = a^{m+n}$
Use the rule above to obtain:
$=[35 \cdot (-\frac{2}{7})]m^{4+1}n^{1+2}
\\=[35 \cdot (-\frac{2}{7})]m^5n^3$
Cancel the common factor $7$ to obtain:
$\require{cancel}\\=[\cancel{35}^5 \cdot (-\frac{2}{\cancel{7}})]m^5n^3
\\=-10m^5n^3$