Brandon has pennies, nickels, and dimes. He has a total of $10.20. There's are three times as many pennies as nickels. There are six times as many dimes as nickels. How many of each coin does he have?
p+5n+10d = 1020
p = 3n
d = 6n
Now just solve as usual
3n + 5n + 10 (6n) = 1020
8n + 60n = 1020
68n = 1020
n = 15
p = 3n = 45
d = 6n = 80