since your solving for x you have to get x on the same side by itself.
x+16=9x
begin by subtracting x from both sides which gives you: 16=9x-x or 16=8x
then divide by 8 from both sides so: 16/8=8/8x
which equals 2=x
plug 2 back into the original equation to be sure:
2+16=9(2)
18=18 so x=2
