| 2 | ( | 55 | − | t | ) | = | 2 | ( | t | − | 40 | ) |
| 方程左边 = | 2 | × | 55 | − | 2 | t |
| = | 110 | − | 2 | t |
| 110 | − | 2 | t | = | 2 | ( | t | − | 40 | ) |
| 方程右边 = | 2 | t | − | 2 | × | 40 |
| = | 2 | t | − | 80 |
| 110 | − | 2 | t | = | 2 | t | − | 80 |
| - | 2 | t | − | 2 | t | = | - | 80 | − | 110 |
| - | 4 | t | = | - | 80 | − | 110 |
| - | 4 | t | = | - | 190 |
| 190 | = | 4 | t |
| 4 | t | = | 190 |
| t | = | 190 | ÷ | 4 |
| = | 190 | × | 1 4 |
| = | 95 | × | 1 2 |
| t | = | 95 2 |
| t | = | 47.5 |