| 800 | ( | 1 | + | m | ) | × | 1000 | ( | 1 | + | 1 2 | m | ) | = | 660000 |
| 方程左边 = | 800000 | ( | 1 | + | m | ) | ( | 1 | + | 1 2 | m | ) |
| 800000 | ( | 1 | + | m | ) | ( | 1 | + | 1 2 | m | ) | = | 660000 |
| 方程左边 = | 800000 | × | 1 | ( | 1 | + | 1 2 | m | ) | + | 800000 | m | ( | 1 | + | 1 2 | m | ) |
| = | 800000 | ( | 1 | + | 1 2 | m | ) | + | 800000 | m | ( | 1 | + | 1 2 | m | ) |
| = | 800000 | × | 1 | + | 800000 | × | 1 2 | m | + | 800000 | m | ( | 1 | + | 1 2 | m | ) |
| = | 800000 | + | 400000 | m | + | 800000 | m | ( | 1 | + | 1 2 | m | ) |
| = | 800000 | + | 400000 | m | + | 800000 | m | × | 1 | + | 800000 | m | × | 1 2 | m |
| = | 800000 | + | 400000 | m | + | 800000 | m | + | 400000 | m | m |
| = | 800000 | + | 1200000 | m | + | 400000 | m | m |
| 800000 | + | 1200000 | m | + | 400000 | m | m | = | 660000 |