when 1/3 is in the power, it means to cube root
when 1/2 is in the power, it means to square root
81^1/2 is the same as √81
√81 = 9
64^1/3 is the same as ∛64
∛64 = 4
Remember that you are adding. Combine the terms.
9 + 4 = 13
B) 13 is your answer
hope this helps