| x | + | ( | 1 | + | 1 | ÷ | 5 | ) | + | ( | 1 | − | 1 | ÷ | 5 | × | x | ) | = | 138 |
| 方程左边 = | x | + | 1 | + | 1 | ÷ | 5 | + | ( | 1 | − | 1 | ÷ | 5 | × | x | ) |
| = | x | + | 1 | + | 1 5 | + | ( | 1 | − | 1 | ÷ | 5 | × | x | ) |
| = | x | + | 6 5 | + | ( | 1 | − | 1 | ÷ | 5 | × | x | ) |
| = | x | + | 6 5 | + | 1 | − | 1 | ÷ | 5 | × | x |
| = | x | + | 6 5 | + | 1 | − | 1 5 | x |
| = | 4 5 | x | + | 11 5 |
4 5 | x | + | 11 5 | = | 138 |
4 5 | x | = | 138 | − | 11 5 |
4 5 | x | = | 679 5 |
| x | = | 679 5 | ÷ | 4 5 |
| = | 679 5 | × | 5 4 |
| = | 679 | × | 1 4 |
| x | = | 679 4 |
| x | = | 169.75 |