we have that
(w^5*z^2)*(-9*w^2*z^5)
Multiplying exponential expressions
we know that
w^5 multiplied by w^2 = w^(5 + 2) = w^7
and
z^2 multiplied by z^5 = z^(2 + 5) = z^7
therefore
(w^5*z^2)*(-9*w^2*z^5) =-9*( w^7)*( z^7)
-9*( w^7)*( z^7)=-(3^2)*( w^7)*( z^7)
the answer is
-(3^2)*( w^7)*( z^7