(x + 4) / ( x + 5) = ( x + 5) / (2x) cross-multiply
2x ( x + 4) = ( x + 5) ( x + 5)
2x^2 + 8x = x^2 + 10x + 25 rearrange as
x^2 - 2x = 25 complete the square on x
x^2 - 2x + 1 = 25 + 1
(x - 1)^2 = 26 take both roots
x - 1 = ±sqrt (26)
x = 1 ± sqrt (26)