| 120 | ÷ | x | − | 1 | ÷ | 10 | = | x | ÷ | ( | x | − | 40 | ) |
| Multiply both sides of the equation by: | x | , | ( | x | − | 40 | ) |
| 120 | ( | x | − | 40 | ) | − | 1 | ÷ | 10 | × | x | ( | x | − | 40 | ) | = | x | x |
| 120 | x | − | 120 | × | 40 | − | 1 | ÷ | 10 | × | x | ( | x | − | 40 | ) | = | x | x |
| 120 | x | − | 4800 | − | 1 10 | x | ( | x | − | 40 | ) | = | x | x |
| 120 | x | − | 4800 | − | 1 10 | x | x | + | 1 10 | x | × | 40 | = | x | x |
| 120 | x | − | 4800 | − | 1 10 | x | x | + | 4 | x | = | x | x |
| 124 | x | − | 4800 | − | 1 10 | x | x | = | x | x |