(a^-5 b/ab^3)-4 simplify with positive exponents

Question

(a^-5 b/ab^3)-4 need to see how to get answer.

Answer 1

If the problem is:  

(  (a^-5 * b) / (a * b^3)  ) -4

Then the answer is:

(  a^-6 * b^-2  ) -4

(  (1/a)^6 * (1/b)^2  ) -4

 

If the problem is:

(  (a^-5 * b) / (a * b^3)  ) ^-4

Then the answer is:

(  (1/a)^6 * (1/b)^2  ) ^-4

(1/a)^-24 * (1/b)^-8

a^24 * b^8