| 52 | X | + | 28 | ( | 30 | − | X | ) | = | 980 |
| 方程左边 = | 52 | X | + | 28 | × | 30 | − | 28 | X |
| = | 52 | X | + | 840 | − | 28 | X |
| = | 24 | X | + | 840 |
| 24 | X | + | 840 | = | 980 |
| 24 | X | = | 980 | − | 840 |
| 24 | X | = | 140 |
| X | = | 140 | ÷ | 24 |
| = | 140 | × | 1 24 |
| = | 35 | × | 1 6 |
| X | = | 35 6 |
| X | = | 5.833333 |
| X | + | ( | 30 | − | X | ) | = | 30 |
| 方程左边 = | X | + | 30 | − | X |
| = | 0 | X | + | 30 |
| 30 | = | 30 |
| = | 30 | − | 30 |