| ( | 5 | ( | 7 | + | X | ) | + | 1 | × | 2 | ) | ÷ | ( | 9 | + | X | ) | = | 24 5 |
| 方程两边同时乘以: | ( | 9 | + | X | ) |
| ( | 5 | ( | 7 | + | X | ) | + | 1 | × | 2 | ) | = | 24 5 | ( | 9 | + | X | ) |
| 5 | ( | 7 | + | X | ) | + | 1 | × | 2 | = | 24 5 | ( | 9 | + | X | ) |
| 5 | ( | 7 | + | X | ) | + | 1 | × | 2 | = | 24 5 | × | 9 | + | 24 5 | X |
| 5 | ( | 7 | + | X | ) | + | 2 | = | 216 5 | + | 24 5 | X |
| 5 | × | 7 | + | 5 | X | + | 2 | = | 216 5 | + | 24 5 | X |
| 35 | + | 5 | X | + | 2 | = | 216 5 | + | 24 5 | X |
| 37 | + | 5 | X | = | 216 5 | + | 24 5 | X |
| 5 | X | − | 24 5 | X | = | 216 5 | − | 37 |
1 5 | X | = | 216 5 | − | 37 |
1 5 | X | = | 31 5 |
| X | = | 31 5 | ÷ | 1 5 |
| = | 31 5 | × | 5 |
| = | 31 | × | 1 |
| X | = | 31 |