| 4000 | ÷ | ( | ( | 380 | + | x | ) | ÷ | 2 | ) | = | 10 |
| 方程两边同时乘以: | ( | ( | 380 | + | x | ) | ÷ | 2 | ) |
| 4000 | = | 10 | ( | ( | 380 | + | x | ) | ÷ | 2 | ) |
| 4000 | = | 10 | ( | 380 | + | x | ) | ÷ | 2 |
| 4000 | = | 5 | ( | 380 | + | x | ) |
| 4000 | = | 5 | × | 380 | + | 5 | x |
| 4000 | = | 1900 | + | 5 | x |
| - | 5 | x | = | 1900 | − | 4000 |
| - | 5 | x | = | - | 2100 |
| 2100 | = | 5 | x |
| 5 | x | = | 2100 |
| x | = | 2100 | ÷ | 5 |
| = | 2100 | × | 1 5 |
| = | 420 | × | 1 |
| x | = | 420 |