A vending machine has twice as many quarters in it as dollar bills. If the quarters and dollar bills have a combined value of $96.00 , how many quarters are in the machine?

Call N = the number of dollars 2N the number of quaters.....so we have

,25(2N) + 1N = 96

1.50N = 96

N = 96 / 1,50 = 64 dollars

2(64) = 128 quarters