Hartley and Bertha are pooling their money to buy their mother a birthday present. (Her birthday, by coincidence, turned out to be the day she was elected to the school board.) The two have $20.25 between them. Hartley has all of his money in dimes and Bertha’s is in quarters. Hartley has twice as many dimes as Bertha has quarters. How much money is Hartley contributing?
Say Hartley has 2x dimes and Bertha has x quarters. Then their money is
| Check: | 45(0.25) = | 11.25 |
| 90(0.10) = | 9.00 | |
| $20.25 |