I need help with this simplify problem

Answer:
Step-by-step explanation:
Numerator = y/ab - ab
= y/ab - ab * ab/ab (LCM = ab)
= (y - a²b²)/ab
Denominator = 1/a - a/b
= 1*b/a*b - a*a/b*a (LCM = ab)
= (b-a²)/ab
(y/ab - ab ) / ( 1/a - 1/b) = (y - a²b²)/ab * ab/ (b-a²)
= (y - a²b²)/ (b-a²)