| 18000 | ÷ | x | = | 12600 | ÷ | ( | x | − | 120 | ) |
| Multiply both sides of the equation by: | x | , | ( | x | − | 120 | ) |
| 18000 | ( | x | − | 120 | ) | = | 12600 | x |
| 18000 | x | − | 18000 | × | 120 | = | 12600 | x |
| 18000 | x | − | 2160000 | = | 12600 | x |
| 18000 | x | − | 12600 | x | = | 2160000 |
| 5400 | x | = | 2160000 |
| x | = | 2160000 | ÷ | 5400 |
| = | 2160000 | × | 1 5400 |
| = | 400 | × | 1 |
| x | = | 400 |