| 0 | = | 380 | q | − | ( | ( | 120 | + | 70 | ) | q | + | 2850000 | ) |
| 方程右边 = | 380 | q | − | ( | 120 | + | 70 | ) | q | − | 2850000 |
| = | 380 | q | − | 120 | q | − | 70 | q | − | 2850000 |
| = | 190 | q | − | 2850000 |
| 0 | = | 190 | q | − | 2850000 |
| - | 190 | q | = | - | 2850000 | − | 0 |
| - | 190 | q | = | - | 2850000 |
| 2850000 | = | 190 | q |
| 190 | q | = | 2850000 |
| q | = | 2850000 | ÷ | 190 |
| = | 2850000 | × | 1 190 |
| = | 15000 | × | 1 |
| q | = | 15000 |