| ( | 380 | x | − | 70 | x | ) | − | ( | 2850000 | + | 120 | x | ) | = | 0 |
| 方程左边 = | 380 | x | − | 70 | x | − | ( | 2850000 | + | 120 | x | ) |
| = | 310 | x | − | ( | 2850000 | + | 120 | x | ) |
| = | 310 | x | − | 2850000 | − | 120 | x |
| = | 190 | x | − | 2850000 |
| 190 | x | − | 2850000 | = | 0 |
| 190 | x | = | 0 | + | 2850000 |
| 190 | x | = | 2850000 |
| x | = | 2850000 | ÷ | 190 |
| = | 2850000 | × | 1 190 |
| = | 15000 | × | 1 |
| x | = | 15000 |