Answer:
9
Step-by-step explanation:
find the surface area : SA = 2LW + 2LH + 2WH
This is a cube, so the length, width and height will be the same
SA = 2s^2 + 2s^2 + 2s^2
SA = 6s^2
486 = 6s^2
486/6 = 6s^2/6
81 = s^2
Take the square root of both sides.
9 = s