| 2800 | ÷ | x | − | 1600 | ÷ | ( | x | ÷ | 7 2 | ) | = | 4 |
| Multiply both sides of the equation by: | x |
| 2800 | − | 1600 | ÷ | ( | 1 | ÷ | 7 2 | ) | × | 1 | = | 4 | x |
| Multiply both sides of the equation by: | ( | 1 | ÷ | 7 2 | ) |
| 2800 | ( | 1 | ÷ | 7 2 | ) | − | 1600 | × | 1 | = | 4 | x | ( | 1 | ÷ | 7 2 | ) |
| 2800 | × | 1 | ÷ | 7 2 | − | 1600 | × | 1 | = | 4 | x | ( | 1 | ÷ | 7 2 | ) |
| 2800 | × | 1 | ÷ | 7 2 | − | 1600 | × | 1 | = | 4 | x | × | 1 | ÷ | 7 2 |
| 800 | − | 1600 | = | 8 7 | x |
| - | 800 | = | 8 7 | x |
8 7 | x | = | - | 800 |
| x | = | - | 800 | ÷ | 8 7 |
| = | - | 800 | × | 7 8 |
| = | - | 100 | × | 7 |
| x | = | - | 700 |