| ( | 12 5 | + | x | ) | ÷ | ( | 12 | + | x | ) | = | 1 4 |
| Multiply both sides of the equation by: | ( | 12 | + | x | ) |
| ( | 12 5 | + | x | ) | = | 1 4 | ( | 12 | + | x | ) |
12 5 | + | x | = | 1 4 | ( | 12 | + | x | ) |
12 5 | + | x | = | 1 4 | × | 12 | + | 1 4 | x |
12 5 | + | x | = | 3 | + | 1 4 | x |
| x | − | 1 4 | x | = | 3 | − | 12 5 |
3 4 | x | = | 3 | − | 12 5 |
3 4 | x | = | 3 5 |
| x | = | 3 5 | ÷ | 3 4 |
| = | 3 5 | × | 4 3 |
| = | 1 5 | × | 4 |
| x | = | 4 5 |
| x | = | 0.8 |