Independent variable effects (or affects?) the value of the dependent variable any change in the indepdent vairable forces a change on the depdent variable it doesn't always go either way
number of cans=8 times dollars spent the number of cans does effect the amount you have to pay but the amount you have effects the number of cans you can buy the amount you pay effects how many cans you can buy
normally, independent is input and depdendent is output input x money, get y cans not input y cans, get x money it could be argued that input y cans, have to pay x money but it is more of an ouput, more than a bill