| 15 | + | 1 | ÷ | 2 | × | 6 | ( | - | 5 | a | − | 10 | ) | = | 30 |
| Left side of the equation = | 15 | + | 3 | ( | - | 5 | a | − | 10 | ) |
| 15 | + | 3 | ( | - | 5 | a | − | 10 | ) | = | 30 |
| Left side of the equation = | 15 | − | 3 | × | 5 | a | − | 3 | × | 10 |
| = | 15 | − | 15 | a | − | 30 |
| = | - | 15 | − | 15 | a |
| - | 15 | − | 15 | a | = | 30 |
| - | 15 | a | = | 30 | + | 15 |
| - | 15 | a | = | 45 |
| - | 45 | = | 15 | a |
| 15 | a | = | - | 45 |
| a | = | - | 45 | ÷ | 15 |
| = | - | 45 | × | 1 15 |
| = | - | 3 | × | 1 |
| a | = | - | 3 |