Answer:
21
Step-by-step explanation:

Expanding the left side gives

which gives two solutions,

and

. But if

, then

, but this number isn't real, so

is an extraneous solution. Meanwhile if

, you get

, so this solution is correct.
"Potential solutions" might refer to both possibilities, but there is only one actual (real) solution.
Answer:
3.375
Step-by-step explanation:
(3/5)^3 / (2/5)^3 = 3.375