| 130 | ( | 6 | x | − | 2000 | ) | + | 50 | × | 40 | × | 100 | = | 642000 |
| 方程左边 = | 130 | ( | 6 | x | − | 2000 | ) | + | 200000 |
| 130 | ( | 6 | x | − | 2000 | ) | + | 200000 | = | 642000 |
| 方程左边 = | 130 | × | 6 | x | − | 130 | × | 2000 | + | 200000 |
| = | 780 | x | − | 260000 | + | 200000 |
| = | 780 | x | − | 60000 |
| 780 | x | − | 60000 | = | 642000 |
| 780 | x | = | 642000 | + | 60000 |
| 780 | x | = | 702000 |
| x | = | 702000 | ÷ | 780 |
| = | 702000 | × | 1 780 |
| = | 900 | × | 1 |
| x | = | 900 |