Consider the equation
(x^m)^3 = (x^13)^5 times (x^-8)^-5.

the value of m is?

a. 15
b. 28
c. 35
d. 70

it's 35, i figured it out

This is the concept of algebra, the value of m will be calculated as follows;
(x^m)^3=(x^13)^5*(x^-8)^-5
expanding the above we get;
x^(3m)=x^(65)*x^(40)
x^(3m)=x^(65+40)
x^(3m)=x^105
the x will cancel out and we shall remain with:
3m=105
dividing both sides by 3 we get;
m=105/3
m=35
You are right the answer is m=35.
Bravo!!