| 33 | ( | 12 | + | 3 | x | ) | = | 10 | ( | 20 | + | 5 | x | ) |
| Left side of the equation = | 33 | × | 12 | + | 33 | × | 3 | x |
| = | 396 | + | 99 | x |
| 396 | + | 99 | x | = | 10 | ( | 20 | + | 5 | x | ) |
| Right side of the equation = | 10 | × | 20 | + | 10 | × | 5 | x |
| = | 200 | + | 50 | x |
| 396 | + | 99 | x | = | 200 | + | 50 | x |
| 99 | x | − | 50 | x | = | 200 | − | 396 |
| 49 | x | = | 200 | − | 396 |
| 49 | x | = | - | 196 |
| x | = | - | 196 | ÷ | 49 |
| = | - | 196 | × | 1 49 |
| = | - | 4 | × | 1 |
| x | = | - | 4 |