| ( | 1 | ÷ | 40 | ) | × | 4 | + | ( | ( | 1 | ÷ | 40 | ) | + | ( | 1 | ÷ | 40 | ) | ) | x | = | 1 |
| 方程左边 = | 1 | ÷ | 40 | × | 4 | + | ( | ( | 1 | ÷ | 40 | ) | + | ( | 1 | ÷ | 40 | ) | ) | x |
| = | 1 10 | + | ( | ( | 1 | ÷ | 40 | ) | + | ( | 1 | ÷ | 40 | ) | ) | x |
| = | 1 10 | + | ( | 1 | ÷ | 40 | ) | x | + | ( | 1 | ÷ | 40 | ) | x |
| = | 1 10 | + | 1 | ÷ | 40 | × | x | + | ( | 1 | ÷ | 40 | ) | x |
| = | 1 10 | + | 1 40 | x | + | ( | 1 | ÷ | 40 | ) | x |
| = | 1 10 | + | 1 40 | x | + | 1 | ÷ | 40 | × | x |
| = | 1 10 | + | 1 40 | x | + | 1 40 | x |
| = | 1 10 | + | 1 20 | x |
1 10 | + | 1 20 | x | = | 1 |
1 20 | x | = | 1 | − | 1 10 |
1 20 | x | = | 9 10 |
| x | = | 9 10 | ÷ | 1 20 |
| = | 9 10 | × | 20 |
| = | 9 | × | 2 |
| x | = | 18 |