| 640 | − | ( | 200 | × | 157 50 | ) | ÷ | 4 | − | ( | 157 50 | ( | 20 | − | x | ) | ( | 20 | − | x | ) | ) | ÷ | 4 | = | 540 |
| 方程左边 = | 640 | − | 200 | × | 157 50 | × | 1 4 | − | ( | 157 50 | ( | 20 | − | x | ) | ( | 20 | − | x | ) | ) | × | 1 4 |
| = | 640 | − | 157 | − | ( | 157 50 | ( | 20 | − | x | ) | ( | 20 | − | x | ) | ) | × | 1 4 |
| = | 483 | − | ( | 157 50 | ( | 20 | − | x | ) | ( | 20 | − | x | ) | ) | × | 1 4 |
| = | 483 | − | 157 50 | ( | 20 | − | x | ) | ( | 20 | − | x | ) | × | 1 4 |
| = | 483 | − | 157 200 | ( | 20 | − | x | ) | ( | 20 | − | x | ) |
| = | 483 | − | 157 200 | × | 20 | ( | 20 | − | x | ) | + | 157 200 | x | ( | 20 | − | x | ) |
| = | 483 | − | 157 10 | ( | 20 | − | x | ) | + | 157 200 | x | ( | 20 | − | x | ) |
| = | 483 | − | 157 10 | × | 20 | + | 157 10 | x | + | 157 200 | x | ( | 20 | − | x | ) |
| = | 483 | − | 314 | + | 157 10 | x | + | 157 200 | x | ( | 20 | − | x | ) |
| = | 169 | + | 157 10 | x | + | 157 200 | x | ( | 20 | − | x | ) |
| = | 169 | + | 157 10 | x | + | 157 200 | x | × | 20 | − | 157 200 | x | x |
| = | 169 | + | 157 10 | x | + | 157 10 | x | − | 157 200 | x | x |
| = | 169 | + | 157 5 | x | − | 157 200 | x | x |
| 169 | + | 157 5 | x | − | 157 200 | x | x | = | 540 |