so 6x6x6 is 216. 648/216 = 3 so that stays inside the cubed root, and 6 stays on the outside. out of the x^4, one of them goes on the outside and one goes in because the cubed root of three cubed is one. the same rules apply to the y, which two go on the outside, and two on the inside. for the outside: 3 • 6 • x • x • y^2 = 18x^2y^2
the answer is A