| 400 | ÷ | ( | 380 | + | x | ) | ÷ | 2 | = | 10 |
| Multiply both sides of the equation by: | ( | 380 | + | x | ) |
| 400 | ÷ | 2 | = | 10 | ( | 380 | + | x | ) |
| 400 | ÷ | 2 | = | 10 | × | 380 | + | 10 | x |
| 200 | = | 3800 | + | 10 | x |
| - | 10 | x | = | 3800 | − | 200 |
| - | 10 | x | = | 3600 |
| - | 3600 | = | 10 | x |
| 10 | x | = | - | 3600 |
| x | = | - | 3600 | ÷ | 10 |
| = | - | 3600 | × | 1 10 |
| = | - | 360 | × | 1 |
| x | = | - | 360 |