y^20 = (?)^2
We want to find the missing number. Let's first think about how exponents are dealt with. If there are two exponents (ex: (z^5)^2) then the exponents multiply to find your new exponent (ex: z^10).
Therefore, we want the power of y to multiply by 2 and equal 20. The answer is 3) y^10.
(y^10)^2 = y^20
