You either give the nonmembers a £2 fee for aerobic classes or minus the members fee by £1
So, there will be 40 green cars. if we want the ratio to be 1:3, we will need there to b three times as many silver cars as green cars: 40*3=120.
we already have 20 silver, so we need to add 120-20, that is 100 silver cars!
He has $18 left (sorry im have to type 20 letterssss)