| 10 | = | 100 | ( | 300 | − | X | ) | ÷ | ( | 300 | × | 200 | ÷ | 100 | ) |
| 方程两边同时乘以: | ( | 300 | × | 200 | ÷ | 100 | ) |
| 10 | ( | 300 | × | 200 | ÷ | 100 | ) | = | 100 | ( | 300 | − | X | ) |
| 10 | × | 300 | × | 200 | ÷ | 100 | = | 100 | ( | 300 | − | X | ) |
| 10 | × | 300 | × | 200 | ÷ | 100 | = | 100 | × | 300 | − | 100 | X |
| 6000 | = | 30000 | − | 100 | X |
| 100 | X | = | 30000 | − | 6000 |
| 100 | X | = | 24000 |
| X | = | 24000 | ÷ | 100 |
| = | 24000 | × | 1 100 |
| = | 240 | × | 1 |
| X | = | 240 |