| 40 | ÷ | ( | x | − | 40 | ) | = | ( | x | + | 15 | ) | ÷ | ( | 2 | x | − | 15 | ) |
| Multiply both sides of the equation by: | ( | x | − | 40 | ) | , | ( | 2 | x | − | 15 | ) |
| 40 | ( | 2 | x | − | 15 | ) | = | ( | x | + | 15 | ) | ( | x | − | 40 | ) |
| 40 | × | 2 | x | − | 40 | × | 15 | = | ( | x | + | 15 | ) | ( | x | − | 40 | ) |
| 40 | × | 2 | x | − | 40 | × | 15 | = | x | ( | x | − | 40 | ) | + | 15 | ( | x | − | 40 | ) |
| 80 | x | − | 600 | = | x | ( | x | − | 40 | ) | + | 15 | ( | x | − | 40 | ) |
| 80 | x | − | 600 | = | x | x | − | x | × | 40 | + | 15 | ( | x | − | 40 | ) |
| 80 | x | − | 600 | = | x | x | − | 40 | x | + | 15 | x | − | 15 | × | 40 |
| 80 | x | − | 600 | = | x | x | − | 40 | x | + | 15 | x | − | 600 |
| 80 | x | − | 600 | = | x | x | − | 25 | x | − | 600 |
| x2=105 |