| ( | 15 | + | x | ) | ÷ | ( | 35 | + | x | ) | = | 3 | ÷ | 5 |
| Multiply both sides of the equation by: | ( | 35 | + | x | ) |
| ( | 15 | + | x | ) | = | 3 | ÷ | 5 | × | ( | 35 | + | x | ) |
| 15 | + | x | = | 3 | ÷ | 5 | × | ( | 35 | + | x | ) |
| 15 | + | x | = | 3 | ÷ | 5 | × | 35 | + | 3 | ÷ | 5 | × | x |
| 15 | + | x | = | 21 | + | 3 5 | x |
| x | − | 3 5 | x | = | 21 | − | 15 |
2 5 | x | = | 21 | − | 15 |
2 5 | x | = | 6 |
| x | = | 6 | ÷ | 2 5 |
| = | 6 | × | 5 2 |
| = | 3 | × | 5 |
| x | = | 15 |