45x=45*6+(45-9)*(x-6+4)
45x=45*6+36*(x-2)
45x=5*9*6+36x-36*2
45x-36x=30*9-4*9*2
9x=30*9-8*9=(30-8)*9
9x=22*9
x=22*9÷9
x=22