| ( | 11 | + | 7 | x | ) | ÷ | ( | 100 | + | 15 | x | ) | = | 1 5 |
| Multiply both sides of the equation by: | ( | 100 | + | 15 | x | ) |
| ( | 11 | + | 7 | x | ) | = | 1 5 | ( | 100 | + | 15 | x | ) |
| 11 | + | 7 | x | = | 1 5 | ( | 100 | + | 15 | x | ) |
| 11 | + | 7 | x | = | 1 5 | × | 100 | + | 1 5 | × | 15 | x |
| 11 | + | 7 | x | = | 20 | + | 3 | x |
| 7 | x | − | 3 | x | = | 20 | − | 11 |
| 4 | x | = | 20 | − | 11 |
| 4 | x | = | 9 |
| x | = | 9 | ÷ | 4 |
| = | 9 | × | 1 4 |
| x | = | 9 4 |
| x | = | 2.25 |