| 1 | ÷ | d | + | 1 | ÷ | d | + | 1 | + | 1 | ÷ | d | + | 2 | = | 0 |
| Multiply both sides of the equation by: | d |
| 1 | + | 1 | ÷ | 1 | × | 1 | + | 1 | d | + | 1 | ÷ | 1 | × | 1 | + | 2 | d | = | 0 |
| 1 | d | + | 2 | d | = | 0 | − | 1 | − | 1 | ÷ | 1 | × | 1 | − | 1 | ÷ | 1 | × | 1 |
| 1 | d | + | 2 | d | = | 0 | − | 1 | − | 1 | − | 1 |
| 3 | d | = | 0 | − | 1 | − | 1 | − | 1 |
| 3 | d | = | - | 3 |
| d | = | - | 3 | ÷ | 3 |
| = | - | 3 | × | 1 3 |
| = | - | 1 | × | 1 |
| d | = | - | 1 |