| 3 | × | 1200 | x | = | 2 | × | 2000 | ( | 38 | − | x | ) |
| 方程左边 = | 3600 | x |
| 3600 | x | = | 2 | × | 2000 | ( | 38 | − | x | ) |
| 方程右边 = | 4000 | ( | 38 | − | x | ) |
| 3600 | x | = | 4000 | ( | 38 | − | x | ) |
| 方程右边 = | 4000 | × | 38 | − | 4000 | x |
| = | 152000 | − | 4000 | x |
| 3600 | x | = | 152000 | − | 4000 | x |
| 3600 | x | + | 4000 | x | = | 152000 |
| 7600 | x | = | 152000 |
| x | = | 152000 | ÷ | 7600 |
| = | 152000 | × | 1 7600 |
| = | 20 | × | 1 |
| x | = | 20 |