| ( | 3 | a | − | 3 | ) | ( | 1 | + | ( | 1 | ÷ | 3 | ) | a | ) | = | 2 | a |
| Left side of the equation = | 3 | a | ( | 1 | + | ( | 1 | ÷ | 3 | ) | a | ) | − | 3 | ( | 1 | + | ( | 1 | ÷ | 3 | ) | a | ) |
| = | 3 | a | × | 1 | + | 3 | a | ( | 1 | ÷ | 3 | ) | a | − | 3 | ( | 1 | + | ( | 1 | ÷ | 3 | ) | a | ) |
| = | 3 | a | + | 3 | a | ( | 1 | ÷ | 3 | ) | a | − | 3 | ( | 1 | + | ( | 1 | ÷ | 3 | ) | a | ) |
| = | 3 | a | + | 3 | a | × | 1 | ÷ | 3 | × | a | − | 3 | ( | 1 | + | ( | 1 | ÷ | 3 | ) | a | ) |
| = | 3 | a | + | 1 | a | a | − | 3 | ( | 1 | + | ( | 1 | ÷ | 3 | ) | a | ) |
| = | 3 | a | + | 1 | a | a | − | 3 | × | 1 | − | 3 | ( | 1 | ÷ | 3 | ) | a |
| = | 3 | a | + | 1 | a | a | − | 3 | − | 3 | ( | 1 | ÷ | 3 | ) | a |
| = | 3 | a | + | 1 | a | a | − | 3 | − | 3 | × | 1 | ÷ | 3 | × | a |
| = | 3 | a | + | 1 | a | a | − | 3 | − | 1 | a |
| = | 2 | a | + | 1 | a | a | − | 3 |
| 2 | a | + | 1 | a | a | − | 3 | = | 2 | a |