| 4200 | × | 3 20 | ( | x | + | 7 10 | ) | + | 1000 | ( | 3 10 | − | x | ) | + | 1600 | x | + | 25000 | × | 7 10 | = | 16000 | ( | 3 20 | x | + | 3 20 | × | 7 10 | + | 1 | ) |
| 方程左边 = | 630 | ( | x | + | 7 10 | ) | + | 1000 | ( | 3 10 | − | x | ) | + | 1600 | x | + | 17500 |
| 630 | ( | x | + | 7 10 | ) | + | 1000 | ( | 3 10 | − | x | ) | + | 1600 | x | + | 17500 | = | 16000 | ( | 3 20 | x | + | 3 20 | × | 7 10 | + | 1 | ) |
| 方程左边 = | 630 | x | + | 630 | × | 7 10 | + | 1000 | ( | 3 10 | − | x | ) | + | 1600 | x | + | 17500 |
| = | 630 | x | + | 441 | + | 1000 | ( | 3 10 | − | x | ) | + | 1600 | x | + | 17500 |
| = | 2230 | x | + | 17941 | + | 1000 | ( | 3 10 | − | x | ) |
| = | 2230 | x | + | 17941 | + | 1000 | × | 3 10 | − | 1000 | x |
| = | 2230 | x | + | 17941 | + | 300 | − | 1000 | x |
| = | 1230 | x | + | 18241 |
| 1230 | x | + | 18241 | = | 16000 | ( | 3 20 | x | + | 3 20 | × | 7 10 | + | 1 | ) |
| 方程右边 = | 16000 | × | 3 20 | x | + | 16000 | × | 3 20 | × | 7 10 | + | 16000 | × | 1 |
| = | 2400 | x | + | 1680 | + | 16000 |
| = | 2400 | x | + | 17680 |
| 1230 | x | + | 18241 | = | 2400 | x | + | 17680 |
| 1230 | x | − | 2400 | x | = | 17680 | − | 18241 |
| - | 1170 | x | = | 17680 | − | 18241 |
| - | 1170 | x | = | - | 561 |
| 561 | = | 1170 | x |
| 1170 | x | = | 561 |
| x | = | 561 | ÷ | 1170 |
| = | 561 | × | 1 1170 |
| = | 187 | × | 1 390 |
| x | = | 187 390 |
| x | = | 0.479487 |