| ( | 30 | − | 3 | x | ) | ( | 3 | x | + | 2 | ) | = | 336 |
| Left side of the equation = | 30 | ( | 3 | x | + | 2 | ) | − | 3 | x | ( | 3 | x | + | 2 | ) |
| = | 30 | × | 3 | x | + | 30 | × | 2 | − | 3 | x | ( | 3 | x | + | 2 | ) |
| = | 90 | x | + | 60 | − | 3 | x | ( | 3 | x | + | 2 | ) |
| = | 90 | x | + | 60 | − | 3 | x | × | 3 | x | − | 3 | x | × | 2 |
| = | 90 | x | + | 60 | − | 9 | x | x | − | 6 | x |
| = | 84 | x | + | 60 | − | 9 | x | x |
| 84 | x | + | 60 | − | 9 | x | x | = | 336 |