| 5 | ( | 1 | + | 3 | × | a% | ) | × | 120 | ( | 1 | − | 2 | × | 5 100 | ) | + | 15 | ( | 1 | + | 5 | × | a% | ) | × | 16 | ( | 1 | + | 2 | × | 5 | × | a% | ) | = | 840 | ( | 1 | + | 2 | × | a% | ) |
| 方程左边 = | 600 | ( | 1 | + | 3 | × | a% | ) | ( | 1 | − | 2 | × | 5 100 | ) | + | 240 | ( | 1 | + | 5 | × | a% | ) | ( | 1 | + | 2 | × | 5 | × | a% | ) |
| 600 | ( | 1 | + | 3 | × | a% | ) | ( | 1 | − | 2 | × | 5 100 | ) | + | 240 | ( | 1 | + | 5 | × | a% | ) | ( | 1 | + | 2 | × | 5 | × | a% | ) | = | 840 | ( | 1 | + | 2 | × | a% | ) |
| 方程左边 = | 600 | × | 1 | ( | 1 | − | 2 | × | 5 100 | ) | + | 600 | × | 3 | × | a% | ( | 1 | − | 2 | × | 5 100 | ) | + | 240 | ( | 1 | + | 5 | × | a% | ) | ( | 1 | + | 2 | × | 5 | × | a% | ) |
| = | 600 | ( | 1 | − | 2 | × | 5 100 | ) | + | 18 | a | ( | 1 | − | 2 | × | 5 100 | ) | + | 240 | ( | 1 | + | 5 | × | a% | ) | ( | 1 | + | 2 | × | 5 | × | a% | ) |
| = | 600 | × | 1 | − | 600 | × | 2 | × | 5 100 | + | 18 | a | ( | 1 | − | 2 | × | 5 100 | ) | + | 240 | ( | 1 | + | 5 | × | a% | ) | ( | 1 | + | 2 | × | 5 | × | a% | ) |
| = | 600 | − | 60 | + | 18 | a | ( | 1 | − | 2 | × | 5 100 | ) | + | 240 | ( | 1 | + | 5 | × | a% | ) | ( | 1 | + | 2 | × | 5 | × | a% | ) |
| = | 540 | + | 18 | a | ( | 1 | − | 2 | × | 5 100 | ) | + | 240 | ( | 1 | + | 5 | × | a% | ) | ( | 1 | + | 2 | × | 5 | × | a% | ) |
| = | 540 | + | 18 | a | × | 1 | − | 18 | a | × | 2 | × | 5 100 | + | 240 | ( | 1 | + | 5 | × | a% | ) | ( | 1 | + | 2 | × | 5 | × | a% | ) |
| = | 540 | + | 18 | a | − | 9 5 | a | + | 240 | ( | 1 | + | 5 | × | a% | ) | ( | 1 | + | 2 | × | 5 | × | a% | ) |
| = | 540 | + | 81 5 | a | + | 240 | ( | 1 | + | 5 | × | a% | ) | ( | 1 | + | 2 | × | 5 | × | a% | ) |
| = | 540 | + | 81 5 | a | + | 240 | × | 1 | ( | 1 | + | 2 | × | 5 | × | a% | ) | + | 240 | × | 5 | × | a% | ( | 1 | + | 2 | × | 5 | × | a% | ) |
| = | 540 | + | 81 5 | a | + | 240 | ( | 1 | + | 2 | × | 5 | × | a% | ) | + | 12 | a | ( | 1 | + | 2 | × | 5 | × | a% | ) |
| = | 540 | + | 81 5 | a | + | 240 | × | 1 | + | 240 | × | 2 | × | 5 | × | a% | + | 12 | a | ( | 1 | + | 2 | × | 5 | × | a% | ) |
| = | 540 | + | 81 5 | a | + | 240 | + | 24 | a | + | 12 | a | ( | 1 | + | 2 | × | 5 | × | a% | ) |
| = | 780 | + | 201 5 | a | + | 12 | a | ( | 1 | + | 2 | × | 5 | × | a% | ) |
| = | 780 | + | 201 5 | a | + | 12 | a | × | 1 | + | 12 | a | × | 2 | × | 5 | × | a% |
| = | 780 | + | 201 5 | a | + | 12 | a | + | 6 5 | a | a |
| = | 780 | + | 261 5 | a | + | 6 5 | a | a |
| 780 | + | 261 5 | a | + | 6 5 | a | a | = | 840 | ( | 1 | + | 2 | × | a% | ) |
| 方程右边 = | 840 | × | 1 | + | 840 | × | 2 | × | a% |
| = | 840 | + | 84 5 | a |
| 780 | + | 261 5 | a | + | 6 5 | a | a | = | 840 | + | 84 5 | a |