| 400 | ( | 643 10 | − | X | ) | = | 150 | ( | 1653 10 | − | X | ) |
| 方程左边 = | 400 | × | 643 10 | − | 400 | X |
| = | 25720 | − | 400 | X |
| 25720 | − | 400 | X | = | 150 | ( | 1653 10 | − | X | ) |
| 方程右边 = | 150 | × | 1653 10 | − | 150 | X |
| = | 24795 | − | 150 | X |
| 25720 | − | 400 | X | = | 24795 | − | 150 | X |
| - | 400 | X | + | 150 | X | = | 24795 | − | 25720 |
| - | 250 | X | = | 24795 | − | 25720 |
| - | 250 | X | = | - | 925 |
| 925 | = | 250 | X |
| 250 | X | = | 925 |
| X | = | 925 | ÷ | 250 |
| = | 925 | × | 1 250 |
| = | 37 | × | 1 10 |
| X | = | 37 10 |
| X | = | 3.7 |