(ab^2)/(a^2b)^-2

The denominator can be placed in the numerator as long as you take away the negative from -2:

 

So, you end up with: (ab^2)(a^2b)^2...

 

Now, you just have to simplify:

(ab^2)(a^2^2)(b^2)

a*b^2*a^4*b^2

 

a*a^4*b^2*b^2

 

Remember, add exponents for similar bases:

a^5*b^4.