| X | + | 19 | + | ( | 285 | − | X | ) | × | 10 | ÷ | 11 | = | 291 |
| 方程左边 = | X | + | 19 | + | ( | 285 | − | X | ) | × | 10 11 |
| X | + | 19 | + | ( | 285 | − | X | ) | × | 10 11 | = | 291 |
| 方程左边 = | X | + | 19 | + | 285 | × | 10 11 | − | X | × | 10 11 |
| = | X | + | 19 | + | 2850 11 | − | X | × | 10 11 |
| = | 1 11 | X | + | 3059 11 |
1 11 | X | + | 3059 11 | = | 291 |
1 11 | X | = | 291 | − | 3059 11 |
1 11 | X | = | 142 11 |
| X | = | 142 11 | ÷ | 1 11 |
| = | 142 11 | × | 11 |
| = | 142 | × | 1 |
| X | = | 142 |