| ( | 9 | + | x | ) | ÷ | ( | 18 | + | x | ) | = | 11 20 |
| Multiply both sides of the equation by: | ( | 18 | + | x | ) |
| ( | 9 | + | x | ) | = | 11 20 | ( | 18 | + | x | ) |
| 9 | + | x | = | 11 20 | ( | 18 | + | x | ) |
| 9 | + | x | = | 11 20 | × | 18 | + | 11 20 | x |
| 9 | + | x | = | 99 10 | + | 11 20 | x |
| x | − | 11 20 | x | = | 99 10 | − | 9 |
9 20 | x | = | 99 10 | − | 9 |
9 20 | x | = | 9 10 |
| x | = | 9 10 | ÷ | 9 20 |
| = | 9 10 | × | 20 9 |
| = | 1 | × | 2 |
| x | = | 2 |