| 100 | ÷ | ( | 30 | + | x | ) | = | 60 | ÷ | ( | 30 | − | x | ) |
| Multiply both sides of the equation by: | ( | 30 | + | x | ) | , | ( | 30 | − | x | ) |
| 100 | ( | 30 | − | x | ) | = | 60 | ( | 30 | + | x | ) |
| 100 | × | 30 | − | 100 | x | = | 60 | ( | 30 | + | x | ) |
| 100 | × | 30 | − | 100 | x | = | 60 | × | 30 | + | 60 | x |
| 3000 | − | 100 | x | = | 1800 | + | 60 | x |
| - | 100 | x | − | 60 | x | = | 1800 | − | 3000 |
| - | 160 | x | = | 1800 | − | 3000 |
| - | 160 | x | = | - | 1200 |
| 1200 | = | 160 | x |
| 160 | x | = | 1200 |
| x | = | 1200 | ÷ | 160 |
| = | 1200 | × | 1 160 |
| = | 15 | × | 1 2 |
| x | = | 15 2 |
| x | = | 7.5 |