3 2 | ( | 1200 | − | t | ) | = | 21 | ( | t | − | 25 | ) |
| 方程左边 = | 3 2 | × | 1200 | − | 3 2 | t |
| = | 1800 | − | 3 2 | t |
| 1800 | − | 3 2 | t | = | 21 | ( | t | − | 25 | ) |
| 方程右边 = | 21 | t | − | 21 | × | 25 |
| = | 21 | t | − | 525 |
| 1800 | − | 3 2 | t | = | 21 | t | − | 525 |
| - | 3 2 | t | − | 21 | t | = | - | 525 | − | 1800 |
| - | 45 2 | t | = | - | 525 | − | 1800 |
| - | 45 2 | t | = | - | 2325 |
| 2325 | = | 45 2 | t |
45 2 | t | = | 2325 |
| t | = | 2325 | ÷ | 45 2 |
| = | 2325 | × | 2 45 |
| = | 155 | × | 2 3 |
| t | = | 310 3 |
| t | = | 103.333333 |