| ( | X | × | 120000 | − | 165 | × | 120000 | ) | − | ( | 1500000 | + | 250 | × | 120000 | ) | = | 0 |
| 方程左边 = | X | × | 120000 | − | 165 | × | 120000 | − | ( | 1500000 | + | 250 | × | 120000 | ) |
| = | X | × | 120000 | − | 19800000 | − | ( | 1500000 | + | 250 | × | 120000 | ) |
| = | 120000 | X | − | 19800000 | − | 1500000 | − | 250 | × | 120000 |
| = | 120000 | X | − | 19800000 | − | 1500000 | − | 30000000 |
| = | 120000 | X | − | 51300000 |
| 120000 | X | − | 51300000 | = | 0 |
| 120000 | X | = | 0 | + | 51300000 |
| 120000 | X | = | 51300000 |
| X | = | 51300000 | ÷ | 120000 |
| = | 51300000 | × | 1 120000 |
| = | 855 | × | 1 2 |
| X | = | 855 2 |
| X | = | 427.5 |