| 7 | a | − | 10 | ( | a | − | 48 | ) | = | 12 | ( | a | − | 26 | ) | − | 12 | ( | a | − | 48 | ) |
| Left side of the equation = | 7 | a | − | 10 | a | + | 10 | × | 48 |
| = | 7 | a | − | 10 | a | + | 480 |
| = | - | 3 | a | + | 480 |
| - | 3 | a | + | 480 | = | 12 | ( | a | − | 26 | ) | − | 12 | ( | a | − | 48 | ) |
| Right side of the equation = | 12 | a | − | 12 | × | 26 | − | 12 | ( | a | − | 48 | ) |
| = | 12 | a | − | 312 | − | 12 | ( | a | − | 48 | ) |
| = | 12 | a | − | 312 | − | 12 | a | + | 12 | × | 48 |
| = | 12 | a | − | 312 | − | 12 | a | + | 576 |
| = | 0 | a | + | 264 |
| - | 3 | a | + | 480 | = | 264 |
| - | 3 | a | = | 264 | − | 480 |
| - | 3 | a | = | - | 216 |
| 216 | = | 3 | a |
| 3 | a | = | 216 |
| a | = | 216 | ÷ | 3 |
| = | 216 | × | 1 3 |
| = | 72 | × | 1 |
| a | = | 72 |