| 109 | × | 100 | ÷ | X | ÷ | 21 20 | ÷ | 90 | × | 100 | = | 176 |
| 方程两边同时乘以: | X |
| 109 | × | 100 | ÷ | 21 20 | ÷ | 90 | × | 100 | = | 176 | X |
| - | 176 | X | = | - | 109 | × | 100 | ÷ | 21 20 | ÷ | 90 | × | 100 |
| - | 176 | X | = | - | 2180000 189 |
2180000 189 | = | 176 | X |
| 176 | X | = | 2180000 189 |
| X | = | 2180000 189 | ÷ | 176 |
| = | 2180000 189 | × | 1 176 |
| = | 136250 189 | × | 1 11 |
| X | = | 136250 2079 |
| X | = | 65.536316 |