| ( | ( | ( | 40 | − | x | ) | ÷ | 1 2 | ) | × | 6 | ) | ( | x | − | 50 | ) | = | 4800 |
| 方程左边 = | ( | ( | 40 | − | x | ) | ÷ | 1 2 | ) | × | 6 | ( | x | − | 50 | ) |
| = | ( | 40 | − | x | ) | ÷ | 1 2 | × | 6 | ( | x | − | 50 | ) |
| = | ( | 40 | − | x | ) | × | 12 | ( | x | − | 50 | ) |
| = | 40 | × | 12 | ( | x | − | 50 | ) | − | x | × | 12 | ( | x | − | 50 | ) |
| = | 480 | ( | x | − | 50 | ) | − | x | × | 12 | ( | x | − | 50 | ) |
| = | 480 | x | − | 480 | × | 50 | − | x | × | 12 | ( | x | − | 50 | ) |
| = | 480 | x | − | 24000 | − | x | × | 12 | ( | x | − | 50 | ) |
| = | 480 | x | − | 24000 | − | x | × | 12 | x | + | x | × | 12 | × | 50 |
| = | 480 | x | − | 24000 | − | x | × | 12 | x | + | x | × | 600 |
| = | 1080 | x | − | 24000 | − | x | × | 12 | x |
| 1080 | x | − | 24000 | − | x | × | 12 | x | = | 4800 |