| 120 | ÷ | x | = | 80 | ÷ | ( | 80 | − | x | ) |
| Multiply both sides of the equation by: | x | , | ( | 80 | − | x | ) |
| 120 | ( | 80 | − | x | ) | = | 80 | x |
| 120 | × | 80 | − | 120 | x | = | 80 | x |
| 9600 | − | 120 | x | = | 80 | x |
| - | 120 | x | − | 80 | x | = | - | 9600 |
| - | 200 | x | = | - | 9600 |
| 9600 | = | 200 | x |
| 200 | x | = | 9600 |
| x | = | 9600 | ÷ | 200 |
| = | 9600 | × | 1 200 |
| = | 48 | × | 1 |
| x | = | 48 |