| ( | 140 | − | 6 | x | ) | ( | 20 | + | 10 | x | ) | = | 1250 |
| Left side of the equation = | 140 | ( | 20 | + | 10 | x | ) | − | 6 | x | ( | 20 | + | 10 | x | ) |
| = | 140 | × | 20 | + | 140 | × | 10 | x | − | 6 | x | ( | 20 | + | 10 | x | ) |
| = | 2800 | + | 1400 | x | − | 6 | x | ( | 20 | + | 10 | x | ) |
| = | 2800 | + | 1400 | x | − | 6 | x | × | 20 | − | 6 | x | × | 10 | x |
| = | 2800 | + | 1400 | x | − | 120 | x | − | 60 | x | x |
| = | 2800 | + | 1280 | x | − | 60 | x | x |
| 2800 | + | 1280 | x | − | 60 | x | x | = | 1250 |