a ^20 = (a^n)^m
When we have a number raised to a power two time, we can multiply the powers;
(a^n)^m = a ^ (n x m)
So, since both sides have the same base:
a^20 = a^ (nxm)
20 = n x m
So, the product of n and m must be 20
A) -5 x -4 = 20
B) 10 x 10 =100
c) 22 x -2 =-44
d)15 x 5 = 75
The correct answer is A.