81 100 | ÷ | ( | X | − | 1319 100 | ) | = | 9 10 |
| 方程两边同时乘以: | ( | X | − | 1319 100 | ) |
81 100 | = | 9 10 | ( | X | − | 1319 100 | ) |
81 100 | = | 9 10 | X | − | 9 10 | × | 1319 100 |
81 100 | = | 9 10 | X | − | 11871 1000 |
| - | 9 10 | X | = | - | 11871 1000 | − | 81 100 |
| - | 9 10 | X | = | - | 12681 1000 |
12681 1000 | = | 9 10 | X |
9 10 | X | = | 12681 1000 |
| X | = | 12681 1000 | ÷ | 9 10 |
| = | 12681 1000 | × | 10 9 |
| = | 1409 100 | × | 1 |
| X | = | 1409 100 |
| X | = | 14.09 |