solutions for x^2+18=9x

Subtract 9x from both sides

x^2 - 9x + 18  = 0         factor the left side

(x - 6) (x - 3) =  0         set each factor to 0

x - 6 = 0                                  x - 3 = 0   

add 6  to both sides                  add 3 to both sides

x = 6                                       x = 3