Introduce a new variable to make it easier to see how to solve the problem.
Let y = x^(1/4)
Then y^2 = x^(1/2)
Then the equation is
or y =
y = -6 gives us x^(1/4) = -6, which is not possible.
y = 5 gives us x^(1/4) = 5, which makes x = 5^4 = 625.
ANSWER: The problem asks for the sum of the digits of x, which is 6+2+5 = 13.
Of course, if a formal algebraic solution is not required, the recognition that x^(1/4) is the square of x^(1/2) means we are looking for two integers, one the square of the other, whose sum is 30. That obviously is 5 and 25, which means x is 5^4 = 35^2 = 625.