x = 4
Explanation:
sqrt(x) + sqrt(5 + x) = 15 / sqrt(5 + x)
sqrt(5 + x)[sqrt(x) + sqrt(5 + x)] = 15
sqrt(5x + x^2) + 5 + x = 15
sqrt(5x + x^2) = 10 - x
Take square of both sides
5x + x^2 = (10 - x)^2
5x + x^2 = 100 - 20x + x^2
Cancel x^2
5x = 100 - 20x
25x = 100
x = 4
