Question

(1:a+b)-(1:b-a)-(2b:a-b)

Answer 1

= 1 / a+b + 1 / a-b - 2b / a-b = a-b+a+b-2ab-2b^2 / (a+b)(a-b) = 
= 2a-2ab-2b^2 / (a+b)(a-b) = 2(a-ab-b^2) / (a+b)(a-b)