9514 1404 393
Explanation:
Both sides of the equation are squared.
I like this better without fractions, so would multiply by 16 at this point (or earlier).
x^2 -40x +144 = 0
(x -36)(x -4) = 0
x = 4 or 36 . . . . . . x = 4 is extraneous
The solution is x = 36.
