| ( | x | − | 6 | ) | ( | 160 | − | 20 | ( | x | − | 10 | ) | ) | = | 700 |
| 方程左边 = | x | ( | 160 | − | 20 | ( | x | − | 10 | ) | ) | − | 6 | ( | 160 | − | 20 | ( | x | − | 10 | ) | ) |
| = | x | × | 160 | − | x | × | 20 | ( | x | − | 10 | ) | − | 6 | ( | 160 | − | 20 | ( | x | − | 10 | ) | ) |
| = | 160 | x | − | x | × | 20 | x | + | x | × | 20 | × | 10 | − | 6 | ( | 160 | − | 20 | ( | x | − | 10 | ) | ) |
| = | 160 | x | − | x | × | 20 | x | + | x | × | 200 | − | 6 | ( | 160 | − | 20 | ( | x | − | 10 | ) | ) |
| = | 360 | x | − | x | × | 20 | x | − | 6 | ( | 160 | − | 20 | ( | x | − | 10 | ) | ) |
| = | 360 | x | − | x | × | 20 | x | − | 6 | × | 160 | + | 6 | × | 20 | ( | x | − | 10 | ) |
| = | 360 | x | − | x | × | 20 | x | − | 960 | + | 120 | ( | x | − | 10 | ) |
| = | 360 | x | − | x | × | 20 | x | − | 960 | + | 120 | x | − | 120 | × | 10 |
| = | 360 | x | − | x | × | 20 | x | − | 960 | + | 120 | x | − | 1200 |
| = | 480 | x | − | x | × | 20 | x | − | 2160 |
| 480 | x | − | x | × | 20 | x | − | 2160 | = | 700 |