Jack chooses 15 downloads for $19.75, and jim chooses 40 downloads for $43.50. what is the regristration fee, and what is the cost of each download?

Registration fee  = x
cost of one download = y

x+15y=19.75
x+40y=43.50

      x+15y=19.75
    -(x+40y=43.50)
         - 25y = 19.75-43.50

          -25y = -23.75
               y = 0.95

x+15y=19.75
x+15*0.95=19.75
x= 19.75 - 15*0.95
x=5.50

registration fee  = $ 5.50
cost of one download = $ 0.95

If there are four friends then each would get, 1.25 or 1 1/4. so this is how i solved 5 ÷ 4 = 1.25 . hope this ; )