| ( | a | − | 1 | ) | ÷ | ( | a | + | 1 | ) | = | 4 | ÷ | 9 |
| Multiply both sides of the equation by: | ( | a | + | 1 | ) |
| ( | a | − | 1 | ) | = | 4 | ÷ | 9 | × | ( | a | + | 1 | ) |
| a | − | 1 | = | 4 | ÷ | 9 | × | ( | a | + | 1 | ) |
| a | − | 1 | = | 4 | ÷ | 9 | × | a | + | 4 | ÷ | 9 | × | 1 |
| a | − | 1 | = | 4 9 | a | + | 4 9 |
| a | − | 4 9 | a | = | 4 9 | + | 1 |
5 9 | a | = | 4 9 | + | 1 |
5 9 | a | = | 13 9 |
| a | = | 13 9 | ÷ | 5 9 |
| = | 13 9 | × | 9 5 |
| = | 13 | × | 1 5 |
| a | = | 13 5 |
| a | = | 2.6 |