M+ 1/n = (mn+1)/n
x/y - x = (x-xy) /y = x(1-y) / y
(a²+b)/a - a = (a²+b -a²)/a = b/a
a- (a-ab) /b = (ab-a+ab) /b = 2a(2b-1) / b
(2a²b-b)/a - ab= (2a²b -b -a²b) /a =
= (a²b-b)/a = b (a²-1) /a = b (a-b)(a+b) / a
a-b/x-a/x² = (ax²-bx-a) / x²
5- 1/x- 1/y = (5xy -y-x) / xy
a- (a-1)/2 +(a-2)/3= (6a-3(a-1) +2(a-2) )/ 6=
= (6a-3a+3+2a-4)/6 = (5a-1)/6