| ( | 1 | ÷ | 40 | ) | × | 4 | + | ( | ( | 1 | ÷ | 40 | ) | + | ( | 1 | ÷ | 50 | ) | ) | x | = | 1 |
| 方程左边 = | 1 | ÷ | 40 | × | 4 | + | ( | ( | 1 | ÷ | 40 | ) | + | ( | 1 | ÷ | 50 | ) | ) | x |
| = | 1 10 | + | ( | ( | 1 | ÷ | 40 | ) | + | ( | 1 | ÷ | 50 | ) | ) | x |
| = | 1 10 | + | ( | 1 | ÷ | 40 | ) | x | + | ( | 1 | ÷ | 50 | ) | x |
| = | 1 10 | + | 1 | ÷ | 40 | × | x | + | ( | 1 | ÷ | 50 | ) | x |
| = | 1 10 | + | 1 40 | x | + | ( | 1 | ÷ | 50 | ) | x |
| = | 1 10 | + | 1 40 | x | + | 1 | ÷ | 50 | × | x |
| = | 1 10 | + | 1 40 | x | + | 1 50 | x |
| = | 1 10 | + | 9 200 | x |
1 10 | + | 9 200 | x | = | 1 |
9 200 | x | = | 1 | − | 1 10 |
9 200 | x | = | 9 10 |
| x | = | 9 10 | ÷ | 9 200 |
| = | 9 10 | × | 200 9 |
| = | 1 | × | 20 |
| x | = | 20 |