The question is ambiguous. The answer could be
5a3
or
(5a)3 = 53a3 or 125a3
22 cubed = 223
316 is the standard form of six cubed if exponential form the answer is 6³
6 cubed = 63
93
223
15^3
9^3
53
15^3
2 to the power of 4
223 = 10648
5 cubed = 5 x 5 x 5 = 53