Yadeliz collects 20-cent and 50-cent coins. The total value of her coins is currently $9.70. If Yadeliz has 4 more 50-cent coins than 20-cent coins, how many of each type does she have?

Answer 1

20x + 50y = 970

y=4+x

x=y-4

20(y-4) + 50y = 970

-80 + 20 y + 50y = 970

70y = 1050

y = 1050/70 = 15

x=11