a + ab^2 = 40b
a - ab^2 = -32b
Add the equations
2a = 8b → a = 4b
Sub this into the first equation
4b + 4b^3 = 40b divide through by 4
b + b^3 = 10b rearrange
b^3 - 9b = 0 factor
b ( b^2 - 9) = 0 → b = 0 or b = -3 or b = 4
So.....a = 4b =
0 , -12 or 12
