This is the concept of simultaneous equations. Let the number of dimes be x and that of quarters by y.
1 quarter =$0.25
1 dime=$0.1
Total number of coins in piggy bank
x+y=64
thus
x=64-y.........i
Total amount will be:
0.1x+0.25y=10.30......ii
substituting i in ii and solve for y we get:
0.1(64-y)+0.25y=10.30
6.4-0.1y+0.25y=10.30
0.15y=10.30-6.4
0.15y=3.9
y=3.9/0.15
y=26
hence:
x=64-y=64-26=38
Therefore we conclude that there are 38 dimes and 26 quarters
