| ( | 120 | − | x | ) | ÷ | ( | - | 120 | − | x | ) | = | 40 | ÷ | 60 |
| Multiply both sides of the equation by: | ( | - | 120 | − | x | ) |
| ( | 120 | − | x | ) | = | 40 | ÷ | 60 | × | ( | - | 120 | − | x | ) |
| 120 | − | x | = | 40 | ÷ | 60 | × | ( | - | 120 | − | x | ) |
| 120 | − | x | = | - | 40 | ÷ | 60 | × | 120 | − | 40 | ÷ | 60 | × | x |
| 120 | − | x | = | - | 80 | − | 2 3 | x |
| - | x | + | 2 3 | x | = | - | 80 | − | 120 |
| - | 1 3 | x | = | - | 80 | − | 120 |
| - | 1 3 | x | = | - | 200 |
| 200 | = | 1 3 | x |
1 3 | x | = | 200 |
| x | = | 200 | ÷ | 1 3 |
| = | 200 | × | 3 |
| x | = | 600 |