| ( | 50 | − | 3 | x | ) | ( | 5000 | + | 20 | x | ÷ | 3 | ) | + | 100 | x | ( | 5000 | − | 20 | x | ÷ | 3 | ) | = | 49000 |
| 方程左边 = | 50 | ( | 5000 | + | 20 | x | ÷ | 3 | ) | − | 3 | x | ( | 5000 | + | 20 | x | ÷ | 3 | ) | + | 100 | x | ( | 5000 | − | 20 | x | ÷ | 3 | ) |
| = | 50 | × | 5000 | + | 50 | × | 20 | x | ÷ | 3 | − | 3 | x | ( | 5000 | + | 20 | x | ÷ | 3 | ) | + | 100 | x | ( | 5000 | − | 20 | x | ÷ | 3 | ) |
| = | 250000 | + | 1000 3 | x | − | 3 | x | ( | 5000 | + | 20 | x | ÷ | 3 | ) | + | 100 | x | ( | 5000 | − | 20 | x | ÷ | 3 | ) |
| = | 250000 | + | 1000 3 | x | − | 3 | x | × | 5000 | − | 3 | x | × | 20 | x | ÷ | 3 | + | 100 |
| = | 250000 | + | 1000 3 | x | − | 15000 | x | − | 20 | x | x | + | 100 | x | ( | 5000 | − | 20 | x | ÷ | 3 | ) |
| = | 250000 | − | 44000 3 | x | − | 20 | x | x | + | 100 | x | ( | 5000 | − | 20 | x | ÷ | 3 | ) |
| = | 250000 | − | 44000 3 | x | − | 20 | x | x | + | 100 | x | × | 5000 | − | 100 | x | × | 20 |
| = | 250000 | − | 44000 3 | x | − | 20 | x | x | + | 500000 | x | − | 2000 3 | x | x |
| = | 250000 | + | 1456000 3 | x | − | 20 | x | x | − | 2000 3 | x | x |
| 250000 | + | 1456000 3 | x | − | 20 | x | x | − | 2000 3 | x | x | = | 49000 |