ok, so the changing aspect it the per hour. so for Naomi it would be 2x. she already has 16.5 . so her equation would be y=2x+16.5 . for Claire, the changing variable would be 4x. she already has 7.5 . her equation would be y=4x+7.5 . both equations are equal to the same variable, so you put them together to make 2x+16.5=4x+7.5 . first you would get rid of the x variables by subtacting the 2 on each side giving you 16.5=2x+7.5 . subract the 7.5 on each side and then divide by 2. then you will get your answer.