| 2 | n | + | 13 | = | ( | n | − | 12 | ) | × | 3 | + | 12 | × | 2 |
| Right side of the equation = | ( | n | − | 12 | ) | × | 3 | + | 24 |
| 2 | n | + | 13 | = | ( | n | − | 12 | ) | × | 3 | + | 24 |
| Right side of the equation = | n | × | 3 | − | 12 | × | 3 | + | 24 |
| = | n | × | 3 | − | 36 | + | 24 |
| = | 3 | n | − | 12 |
| 2 | n | + | 13 | = | 3 | n | − | 12 |
| 2 | n | − | 3 | n | = | - | 12 | − | 13 |
| - | n | = | - | 12 | − | 13 |
| - | n | = | - | 12 | − | 13 |
| - | n | = | - | 25 |
| 25 | = | n |
| n | = | 25 |