Your calculator should give you the answer to both.
3^3 = 3 * 3 * 3 = 27
∛(125) = ∛(5 * 5 * 5) = Three equal factors under a cube root sign give 1 factor on the left of the cube root sign. The other 2 are discarded.
∛(5 * 5 * 5) = 5∛1 = 5
