You need to break the $20 into smaller bills. The smaller bills value has to be equal to $20. So far you have three $5 bills and three 1$ bills, so the current value is 3*$5 + 3*$1= $18
The value you need to add more will be $20- $18= $2
You need to add $2 more value to the smaller bills and you want to do it using quarters($0.25). The number of the quarter you need will be: $2/ $0.25= 8 quarters
