| 50000 | = | X | − | ( | X | ( | 1 | − | 20 | ) | × | 2 5 | − | 7000 | ) |
| 方程右边 = | X | − | X | ( | 1 | − | 20 | ) | × | 2 5 | + | 7000 |
| = | X | − | X | × | 1 | × | 2 5 | + | X | × | 20 | × | 2 5 | + | 7000 |
| = | X | − | X | × | 2 5 | + | X | × | 8 | + | 7000 |
| = | 43 5 | X | + | 7000 |
| 50000 | = | 43 5 | X | + | 7000 |
| - | 43 5 | X | = | 7000 | − | 50000 |
| - | 43 5 | X | = | - | 43000 |
| 43000 | = | 43 5 | X |
43 5 | X | = | 43000 |
| X | = | 43000 | ÷ | 43 5 |
| = | 43000 | × | 5 43 |
| = | 1000 | × | 5 |
| X | = | 5000 |