| 9000 | ( | 1 | − | 2 | × | x% | ) | ( | 1 | + | x% | ) | + | 8000 | ( | 1 | + | 3 | × | x% | ) | ( | 1 | − | x% | ) | − | 17000 | = | 0 |
| 方程左边 = | 9000 | × | 1 | ( | 1 | + | x% | ) | − | 9000 | × | 2 | × | x% | ( | 1 | + | x% | ) | + | 8000 | ( | 1 | + | 3 | × | x% | ) | ( | 1 | − | x% | ) | − | 17000 |
| = | 9000 | ( | 1 | + | x% | ) | − | 180 | x | ( | 1 | + | x% | ) | + | 8000 | ( | 1 | + | 3 | × | x% | ) | ( | 1 | − | x% | ) | − | 17000 |
| = | 9000 | × | 1 | + | 9000 | × | x% | − | 180 | x | ( | 1 | + | x% | ) | + | 8000 | ( | 1 | + | 3 | × | x% | ) | ( | 1 | − | x% | ) | − | 17000 |
| = | 9000 | + | 90 | x | − | 180 | x | ( | 1 | + | x% | ) | + | 8000 | ( | 1 | + | 3 | × | x% | ) | ( | 1 | − | x% | ) | − | 17000 |
| = | - | 8000 | + | 90 | x | − | 180 | x | ( | 1 | + | x% | ) | + | 8000 | ( | 1 | + | 3 | × | x% | ) | ( | 1 | − | x% | ) |
| = | - | 8000 | + | 90 | x | − | 180 | x | × | 1 | − | 180 | x | × | x% | + | 8000 | ( | 1 | + | 3 | × | x% | ) | ( | 1 | − | x% | ) |
| = | - | 8000 | + | 90 | x | − | 180 | x | − | 9 5 | x | x | + | 8000 | ( | 1 | + | 3 | × | x% | ) | ( | 1 | − | x% | ) |
| = | - | 8000 | − | 90 | x | − | 9 5 | x | x | + | 8000 | ( | 1 | + | 3 | × | x% | ) | ( | 1 | − | x% | ) |
| = | - | 8000 | − | 90 | x | − | 9 5 | x | x | + | 8000 | × | 1 | ( | 1 | − | x% | ) | + | 8000 | × | 3 | × | x% |
| = | - | 8000 | − | 90 | x | − | 9 5 | x | x | + | 8000 | ( | 1 | − | x% | ) | + | 240 | x | ( | 1 | − | x% | ) |
| = | - | 8000 | − | 90 | x | − | 9 5 | x | x | + | 8000 | × | 1 | − | 8000 | × | x% | + | 240 | x |
| = | - | 8000 | − | 90 | x | − | 9 5 | x | x | + | 8000 | − | 80 | x | + | 240 | x | ( | 1 | − | x% | ) |
| = | - | 0 | − | 170 | x | − | 9 5 | x | x | + | 240 | x | ( | 1 | − | x% | ) |
| = | - | 170 | x | − | 9 5 | x | x | + | 240 | x | × | 1 | − | 240 | x | × | x% |
| = | - | 170 | x | − | 9 5 | x | x | + | 240 | x | − | 12 5 | x | x |
| = | 70 | x | − | 9 5 | x | x | − | 12 5 | x | x |
| 70 | x | − | 9 5 | x | x | − | 12 5 | x | x | = | 0 |
| x2= | 50 3 |