Answer:
m=4
n=-2
Step-by-step explanation:
(7z^m) (nz^3) = -14z^7
7*n z^(m+3) = -14 z^7
We know the constants have to be the same
7n = -14
Divide each side by 7
7n/7 = -14/7
n = -2
And the exponents have to be the same
m+3 = 7
Subtract 3 from each side
m+3-3 = 7-3
m =4
