Alternatively we could do it this way, look at diagram
2 (11 * x) + 2 (25 * x) + 4 x^2 = 576
giving
4 x^2 + 72 x - 576 = 0
We could simplify it to
x^2 + 18 x - 144 = 0
Solve either by hand or
Solve[x^2 + 18 x - 144 == 0, x]
{{x -> -24}, {x -> 6}}
and clearly x can't be -24 so there you have the answer.
Paul.
