| 800 | m | + | 3 5 | × | 750 | ( | 50 | − | m | ) | = | 0 |
| 方程左边 = | 800 | m | + | 450 | ( | 50 | − | m | ) |
| 800 | m | + | 450 | ( | 50 | − | m | ) | = | 0 |
| 方程左边 = | 800 | m | + | 450 | × | 50 | − | 450 | m |
| = | 800 | m | + | 22500 | − | 450 | m |
| = | 350 | m | + | 22500 |
| 350 | m | + | 22500 | = | 0 |
| 350 | m | = | 0 | − | 22500 |
| 350 | m | = | - | 22500 |
| m | = | - | 22500 | ÷ | 350 |
| = | - | 22500 | × | 1 350 |
| = | - | 450 | × | 1 7 |
| m | = | - | 450 7 |
| m | = | - 64.285714 |