99 100 | × | 1 10 | = | 1 20 | ( | X | + | 1 10 | ) |
| 方程左边 = | 99 1000 |
99 1000 | = | 1 20 | ( | X | + | 1 10 | ) |
| 方程右边 = | 1 20 | X | + | 1 20 | × | 1 10 |
| = | 1 20 | X | + | 1 200 |
99 1000 | = | 1 20 | X | + | 1 200 |
| - | 1 20 | X | = | 1 200 | − | 99 1000 |
| - | 1 20 | X | = | - | 47 500 |
47 500 | = | 1 20 | X |
1 20 | X | = | 47 500 |
| X | = | 47 500 | ÷ | 1 20 |
| = | 47 500 | × | 20 |
| = | 47 25 | × | 1 |
| X | = | 47 25 |
| X | = | 1.88 |