| ( | 2 | + | 1 | ÷ | 2 | ) | ( | 3 | ÷ | 2 | + | ( | 2 | ÷ | 3 | + | X | ÷ | 3 | ) | ) | = | 15 | ÷ | 4 |
| 方程左边 = | 2 | ( | 3 | ÷ | 2 | + | ( | 2 | ÷ | 3 | + | X | ÷ | 3 | ) | ) | + | 1 | ÷ | 2 | × | ( | 3 | ÷ | 2 | + | ( | 2 | ÷ | 3 | + | X | ÷ | 3 | ) | ) |
| = | 2 | ( | 3 | ÷ | 2 | + | ( | 2 | ÷ | 3 | + | X | ÷ | 3 | ) | ) | + | 1 2 | ( | 3 | ÷ | 2 | + | ( | 2 | ÷ | 3 | + | X | ÷ | 3 | ) | ) |
| = | 2 | × | 3 | ÷ | 2 | + | 2 | ( | 2 | ÷ | 3 | + | X | ÷ | 3 | ) | + | 1 2 | ( | 3 | ÷ | 2 | + | ( | 2 | ÷ | 3 | + | X | ÷ | 3 | ) | ) |
| = | 3 | + | 2 | ( | 2 | ÷ | 3 | + | X | ÷ | 3 | ) | + | 1 2 | ( | 3 | ÷ | 2 | + | ( | 2 | ÷ | 3 | + | X | ÷ | 3 | ) | ) |
| = | 3 | + | 2 | × | 2 | ÷ | 3 | + | 2 | X | ÷ | 3 | + | 1 2 | ( | 3 | ÷ | 2 | + | ( | 2 | ÷ | 3 | + | X | ÷ | 3 | ) | ) |
| = | 3 | + | 4 3 | + | 2 3 | X | + | 1 2 | ( | 3 | ÷ | 2 | + | ( | 2 | ÷ | 3 | + | X | ÷ | 3 | ) | ) |
| = | 13 3 | + | 2 3 | X | + | 1 2 | ( | 3 | ÷ | 2 | + | ( | 2 | ÷ | 3 | + | X | ÷ | 3 | ) | ) |
| = | 13 3 | + | 2 3 | X | + | 1 2 | × | 3 | ÷ | 2 | + | 1 2 | ( | 2 | ÷ | 3 | + | X | ÷ | 3 | ) |
| = | 13 3 | + | 2 3 | X | + | 3 4 | + | 1 2 | ( | 2 | ÷ | 3 | + | X | ÷ | 3 | ) |
| = | 61 12 | + | 2 3 | X | + | 1 2 | ( | 2 | ÷ | 3 | + | X | ÷ | 3 | ) |
| = | 61 12 | + | 2 3 | X | + | 1 2 | × | 2 | ÷ | 3 | + | 1 2 | X | ÷ | 3 |
| = | 61 12 | + | 2 3 | X | + | 1 3 | + | 1 6 | X |
| = | 65 12 | + | 5 6 | X |
65 12 | + | 5 6 | X | = | 15 | ÷ | 4 |
| 方程右边 = | 15 4 |
65 12 | + | 5 6 | X | = | 15 4 |
5 6 | X | = | 15 4 | − | 65 12 |
5 6 | X | = | - | 5 3 |
| X | = | - | 5 3 | ÷ | 5 6 |
| = | - | 5 3 | × | 6 5 |
| = | - | 1 | × | 2 |
| X | = | - | 2 |