Question 252182
One way to look at this is to try several values. In general we start with the assumption that we use positive integers.

If x = 3, we get 

{{{5^3 - 4^3 = 8^2 - 3}}}

125 - 64 = 64 - 3

61 = 61.

As a footnote, the only answer is 3.

Sorry I don't have a neat algebraic solution for you.