| 900 | ( | 600 | ( | 1 | − | m% | ) | ) | + | 120 | ( | 180 | ( | 1 | − | 5 | ÷ | 9 | × | m% | ) | ) | = | 62400 |
| 方程左边 = | 900 | × | 600 | ( | 1 | − | m% | ) | + | 120 | ( | 180 | ( | 1 | − | 5 | ÷ | 9 | × | m% | ) | ) |
| = | 540000 | ( | 1 | − | m% | ) | + | 120 | ( | 180 | ( | 1 | − | 5 | ÷ | 9 | × | m% | ) | ) |
| = | 540000 | × | 1 | − | 540000 | × | m% | + | 120 | ( | 180 | ( | 1 | − | 5 | ÷ | 9 | × | m% | ) | ) |
| = | 540000 | − | 5400 | m | + | 120 | ( | 180 | ( | 1 | − | 5 | ÷ | 9 | × | m% | ) | ) |
| = | 540000 | − | 5400 | m | + | 120 | × | 180 | ( | 1 | − | 5 | ÷ | 9 | × | m% | ) |
| = | 540000 | − | 5400 | m | + | 21600 | ( | 1 | − | 5 | ÷ | 9 | × | m% | ) |
| = | 540000 | − | 5400 | m | + | 21600 | × | 1 | − | 21600 | × | 5 | ÷ | 9 | × | m% |
| = | 540000 | − | 5400 | m | + | 21600 | − | 120 | m |
| = | 561600 | − | 5520 | m |
| 561600 | − | 5520 | m | = | 62400 |
| - | 5520 | m | = | 62400 | − | 561600 |
| - | 5520 | m | = | - | 499200 |
| 499200 | = | 5520 | m |
| 5520 | m | = | 499200 |
| m | = | 499200 | ÷ | 5520 |
| = | 499200 | × | 1 5520 |
| = | 2080 | × | 1 23 |
| m | = | 2080 23 |
| m | = | 90.434783 |