| ( | 12 | + | x | ) | ÷ | ( | 40 | + | x | ) | = | 1 2 |
| Multiply both sides of the equation by: | ( | 40 | + | x | ) |
| ( | 12 | + | x | ) | = | 1 2 | ( | 40 | + | x | ) |
| 12 | + | x | = | 1 2 | ( | 40 | + | x | ) |
| 12 | + | x | = | 1 2 | × | 40 | + | 1 2 | x |
| 12 | + | x | = | 20 | + | 1 2 | x |
| x | − | 1 2 | x | = | 20 | − | 12 |
1 2 | x | = | 20 | − | 12 |
1 2 | x | = | 8 |
| x | = | 8 | ÷ | 1 2 |
| = | 8 | × | 2 |
| x | = | 16 |