You have to remember that what you do to one side you must do the to the other. You want to isolate the x, so to do that you have to move everything to the other side by and by doing this you do the opposite. You want to remove +20 from the left side, so by doing that you do -20. Your equation is then 5x=80. You still want to isolate just the x, so to do this you divide by 5 and you have to do that to the other side as well. Therefore your answer it x=16 :)
