| ( | 20 | + | 2 | x | ) | ( | 38 | − | x | ) | = | 1150 |
| Left side of the equation = | 20 | ( | 38 | − | x | ) | + | 2 | x | ( | 38 | − | x | ) |
| = | 20 | × | 38 | − | 20 | x | + | 2 | x | ( | 38 | − | x | ) |
| = | 760 | − | 20 | x | + | 2 | x | ( | 38 | − | x | ) |
| = | 760 | − | 20 | x | + | 2 | x | × | 38 | − | 2 | x | x |
| = | 760 | − | 20 | x | + | 76 | x | − | 2 | x | x |
| = | 760 | + | 56 | x | − | 2 | x | x |
| 760 | + | 56 | x | − | 2 | x | x | = | 1150 |