| ( | 380 | + | x | ) | × | 3 5 | = | 380 | + | x | − | 300 |
| 方程左边 = | 380 | × | 3 5 | + | x | × | 3 5 |
| = | 228 | + | x | × | 3 5 |
| 228 | + | 3 5 | x | = | 380 | + | x | − | 300 |
| 方程右边 = | 80 | + | x |
| 228 | + | 3 5 | x | = | 80 | + | x |
3 5 | x | − | x | = | 80 | − | 228 |
| - | 2 5 | x | = | 80 | − | 228 |
| - | 2 5 | x | = | - | 148 |
| 148 | = | 2 5 | x |
2 5 | x | = | 148 |
| x | = | 148 | ÷ | 2 5 |
| = | 148 | × | 5 2 |
| = | 74 | × | 5 |
| x | = | 370 |