| 7 | ( | 80 | − | t | ) | = | 17 | ( | t | − | 56 | ) |
| 方程左边 = | 7 | × | 80 | − | 7 | t |
| = | 560 | − | 7 | t |
| 560 | − | 7 | t | = | 17 | ( | t | − | 56 | ) |
| 方程右边 = | 17 | t | − | 17 | × | 56 |
| = | 17 | t | − | 952 |
| 560 | − | 7 | t | = | 17 | t | − | 952 |
| - | 7 | t | − | 17 | t | = | - | 952 | − | 560 |
| - | 24 | t | = | - | 952 | − | 560 |
| - | 24 | t | = | - | 1512 |
| 1512 | = | 24 | t |
| 24 | t | = | 1512 |
| t | = | 1512 | ÷ | 24 |
| = | 1512 | × | 1 24 |
| = | 63 | × | 1 |
| t | = | 63 |