Apiggy bank contain $5.60 in nickel and dime. the number of nickel is 8 less than 3 time the dime. how many nickel and dime are their in the piggyback?

0.05n + 0.10d = 5.60
n = 3d - 8

0.05(3d - 8) + 0.10d = 5.60
0.15d - 0.40 + 0.10d = 5.60
0.15d + 0.10d = 5.60 + 0.40
0.25d = 6
d = 6 / 0.25
d = 24 <=== there are 24 dimes

n = 3d - 8
n = 3(24) - 8
n = 72 - 8
n = 64 <== there are 64 nickels