| ( | 50 | ( | 1 | + | 20 100 | ) | ) | + | ( | 4 100 | x | ) | = | x |
| 方程左边 = | 50 | ( | 1 | + | 20 100 | ) | + | ( | 4 100 | x | ) |
| = | 50 | × | 1 | + | 50 | × | 20 100 | + | ( | 4 100 | x | ) |
| = | 50 | + | 10 | + | ( | 4 100 | x | ) |
| = | 60 | + | ( | 4 100 | x | ) |
| = | 60 | + | 4 100 | x |
| 60 | + | 4 100 | x | = | x |
4 100 | x | − | x | = | - | 60 |
| - | 24 25 | x | = | - | 60 |
| 60 | = | 24 25 | x |
24 25 | x | = | 60 |
| x | = | 60 | ÷ | 24 25 |
| = | 60 | × | 25 24 |
| = | 5 | × | 25 2 |
| x | = | 125 2 |
| x | = | 62.5 |