| 1 | ÷ | 4 | × | X | + | ( | 2 | ÷ | 5 | × | X | − | 7 | ) | = | X | − | 35 |
| 方程左边 = | 1 4 | X | + | ( | 2 | ÷ | 5 | × | X | − | 7 | ) |
1 4 | X | + | ( | 2 | ÷ | 5 | × | X | − | 7 | ) | = | X | − | 35 |
| 方程左边 = | 1 4 | X | + | 2 | ÷ | 5 | × | X | − | 7 |
| = | 1 4 | X | + | 2 5 | X | − | 7 |
| = | 13 20 | X | − | 7 |
13 20 | X | − | 7 | = | X | − | 35 |
13 20 | X | − | X | = | - | 35 | + | 7 |
| - | 7 20 | X | = | - | 35 | + | 7 |
| - | 7 20 | X | = | - | 28 |
| 28 | = | 7 20 | X |
7 20 | X | = | 28 |
| X | = | 28 | ÷ | 7 20 |
| = | 28 | × | 20 7 |
| = | 4 | × | 20 |
| X | = | 80 |