(5/2)^-2 + (2/1)^-3
Remember that when a fraction (a/b)^-n is considered you can do a couple of things:
1. You can distribute the exponents to both the numerators and the denominators.
2. Flip the fraction in the parantheses and then do #1.
When you do either step 1 or 2, you will have to find the LCD (Lowest common denominator) to combine the fractions.