| Mary | Ann |
| 24 | 18 <-- ages now |
| 18 | 12 <-- ages before |
| --- | BOY | SISTER | EQUATION |
|---|---|---|---|
| now | x | y | x = 2.5 y |
| last year | x - 1 | y - 1 | x - 1 = 3 (y - 1) |
| 2 years ago | x - 2 | y - 2 | x - 2 = 4 (y - 2) |
| 3 years ago | x - 3 | y - 3 | x - 3 = 7 (y - 3) |
| 50¢ | 25¢ | 10¢ | 5¢ | 1¢ |
|---|---|---|---|---|
| --- | --- | --- | 100 | --- |
| --- | --- | 4 | 91 | 5 |
| --- | --- | 8 | 82 | 10 |
| --- | --- | 12 | 73 | 15 |
| --- | --- | 16 | 64 | 20 |
| --- | --- | 20 | 55 | 25 |
| --- | --- | 24 | 46 | 30 |
| --- | --- | 28 | 37 | 35 |
| --- | --- | 32 | 28 | 40 |
| 1 | --- | 39 | --- | 60 |
| 2 | --- | 30 | 8 | 60 |
| --- | 10 | --- | 40 | 50 |
| --- | --- | 40 | 10 | 50 |
| 4 | 1 | 20 | --- | 75 |
| --- | 4 | 16 | 40 | 40 |





