15b-3a/b^2-a^2 divided by a-5b/ab+b^2 - Perform indicated operation

I am not sure how to go about doing the equation...I know that I could flip the second part so it becomes a multiplication question but I am not sure where to go from there.

= [(15b - 3a)/(b² - a²)] / [(a - 5b)/(ab + b²)] → divided by (a/b) it's equal to multiply by (b/a)

= [(15b - 3a)/(b² - a²)] * [(ab + b²)/(a - 5b)] → you multiply the tops together and the bottoms together

= [(15b - 3a)(ab + b²)] / [(b² - a²)(a - 5b)] → you factorize 3

= [3(5b - a)(ab + b²)] / [(b² - a²)(a - 5b)] → you modify the sign

= [- 3(a - 5b)(ab + b²)] / [(b² - a²)(a - 5b)] → you simplify by (a - 5b)

= [- 3(ab + b²)] / (b² - a²) → you factorize b

= [- 3b(a + b)] / (b² - a²) → you know that: (b² - a²) = (b + a)(b - a)

= [- 3b(a + b)] / [(b + a)(b - a)] → you know that: (b + a) = (a + b)

= [- 3b(a + b)] / [(a + b)(b - a)] → you simplify by (a + b)

= [- 3b] / [(b - a)] → you simplify

= - 3b/(b - a) → you simplify

= 3b/(a - b)

15b-3a/b^2-a^2 divided by a-5b/ab+b^2

= -3(-5b + a)/(b+a)(b-a)]/(a-5b)/b(a+b)
= -3(a-5b)/(b+a)(b-a)*b(a+b)/(a-5b) -> [both (a+b)s and (a-5b)s from the numerator and the denominator cancels each other out]
= -3b/(b-a)
= 3b/(a-b) -> [multiplying both the numerator and the denominator by -1]

Answer = 3b/(a-b)