| ( | 19 10 | − | X | ) | × | 100 | = | ( | 490 | − | 120 | ) | ÷ | 12 |
| 方程左边 = | 19 10 | × | 100 | − | X | × | 100 |
| = | 190 | − | X | × | 100 |
| 190 | − | 100 | X | = | ( | 490 | − | 120 | ) | ÷ | 12 |
| 方程右边 = | 490 | × | 1 12 | − | 120 | × | 1 12 |
| = | 245 6 | − | 10 |
| = | 185 6 |
| 190 | − | 100 | X | = | 185 6 |
| - | 100 | X | = | 185 6 | − | 190 |
| - | 100 | X | = | - | 955 6 |
955 6 | = | 100 | X |
| 100 | X | = | 955 6 |
| X | = | 955 6 | ÷ | 100 |
| = | 955 6 | × | 1 100 |
| = | 191 6 | × | 1 20 |
| X | = | 191 120 |
| X | = | 1.591667 |