| 200 | X | = | ( | 200 | + | 20 | ) | ( | X | − | 5 | ) |
| 方程右边 = | 200 | ( | X | − | 5 | ) | + | 20 | ( | X | − | 5 | ) |
| = | 200 | X | − | 200 | × | 5 | + | 20 | ( | X | − | 5 | ) |
| = | 200 | X | − | 1000 | + | 20 | ( | X | − | 5 | ) |
| = | 200 | X | − | 1000 | + | 20 | X | − | 20 | × | 5 |
| = | 200 | X | − | 1000 | + | 20 | X | − | 100 |
| = | 220 | X | − | 1100 |
| 200 | X | = | 220 | X | − | 1100 |
| 200 | X | − | 220 | X | = | - | 1100 |
| - | 20 | X | = | - | 1100 |
| 1100 | = | 20 | X |
| 20 | X | = | 1100 |
| X | = | 1100 | ÷ | 20 |
| = | 1100 | × | 1 20 |
| = | 55 | × | 1 |
| X | = | 55 |