| ( | 800 | + | x | ) | ( | 50 | − | x | ÷ | 25 | ) | = | 42025 |
| 方程左边 = | 800 | ( | 50 | − | x | ÷ | 25 | ) | + | x | ( | 50 | − | x | ÷ | 25 | ) |
| = | 800 | × | 50 | − | 800 | x | ÷ | 25 | + | x | ( | 50 | − | x | ÷ | 25 | ) |
| = | 40000 | − | 32 | x | + | x | ( | 50 | − | x | ÷ | 25 | ) |
| = | 40000 | − | 32 | x | + | x | × | 50 | − | x | x | ÷ | 25 |
| = | 40000 | + | 18 | x | − | x | x | × | 1 25 |
| 40000 | + | 18 | x | − | x | x | × | 1 25 | = | 42025 |
| x1= | 1575 7 |
| x2= | 1575 7 |