| x | ( | - | 2 | x | + | 80 | − | 12 | ) | + | 16 | ( | 50 | − | x | ) | − | 260 | = | 300 |
| 方程左边 = | - | x | × | 2 | x | + | x | × | 80 | − | x | × | 12 | + | 16 | ( | 50 | − | x | ) | − | 260 |
| = | - | x | × | 2 | x | + | 68 | x | + | 16 | ( | 50 | − | x | ) | − | 260 |
| = | - | x | × | 2 | x | + | 68 | x | + | 16 | × | 50 | − | 16 | x | − | 260 |
| = | - | x | × | 2 | x | + | 68 | x | + | 800 | − | 16 | x | − | 260 |
| = | - | x | × | 2 | x | + | 52 | x | + | 540 |
| - | x | × | 2 | x | + | 52 | x | + | 540 | = | 300 |