Let f(x) = 1/(x+7)+15/(x-8). Find all a for which f(a)=f(a+15).

How do I solve this problem?

ok, solve.

f(a)=f(a+15)
1/(7+a) + 15/(a-8) = 1/(a+22) + 15/(a+7)

multiply both sides of the equation by

(a+7)(a-8)(a+22)
and solve.

This is a multiple choice question and I am not getting any of the choices

a.) -161/8
b.) 120/7
c.) 161/7
d.) -17

Nor do I.