X=21 first you subtract out the numbers you have from the total so 180-(3+9) which is 168 so you know 5x+3x=168 so you simplify first add your 5x+3x so 8x=168 then you want to get x by itself so you divide out the 8 so 8x divided by 8 is just x and what you do to one side you must do to the other so 168 divided by 8 is 21
