A^2 -b^2 / a +b
Apply the difference of two squares formula to the top :
A^2 - b^2 = (a+b)(a-b)
now you have :
(A+b)(a-b) / a+b = 12
the two (a+ b)’s cancel each other out so you are left with a-b = 12
answer: a-b = 12
