| ( | x | − | 35 | ) | ( | 650 | − | 10 | x | ) | = | 1760 |
| 方程左边 = | x | ( | 650 | − | 10 | x | ) | − | 35 | ( | 650 | − | 10 | x | ) |
| = | x | × | 650 | − | x | × | 10 | x | − | 35 | ( | 650 | − | 10 | x | ) |
| = | 650 | x | − | x | × | 10 | x | − | 35 | × | 650 | + | 35 | × | 10 | x |
| = | 650 | x | − | x | × | 10 | x | − | 22750 | + | 350 | x |
| = | 1000 | x | − | x | × | 10 | x | − | 22750 |
| 1000 | x | − | x | × | 10 | x | − | 22750 | = | 1760 |