To solve this, you look at the powers of x and take either the square root (if it is to a power of 2) or the cube root (if a power of 3) of both sides to isolate x. For the first equation, you take the square root of 48, so A is correct. For the second one, you take the square root of 63, so B is correct. For the final equation, you take the cube root of 73, so F is correct.
You then have to subtract 125 from both sides so we can isolate our variable which will give us 15x = 120 . Divide 15 from both sides : 15x/15 = 120/15 which will give us x = 8.