| ( | 100 | − | 7 | x | ) | ( | 60 | − | 5 | x | ) | = | 3600 |
| Left side of the equation = | 100 | ( | 60 | − | 5 | x | ) | − | 7 | x | ( | 60 | − | 5 | x | ) |
| = | 100 | × | 60 | − | 100 | × | 5 | x | − | 7 | x | ( | 60 | − | 5 | x | ) |
| = | 6000 | − | 500 | x | − | 7 | x | ( | 60 | − | 5 | x | ) |
| = | 6000 | − | 500 | x | − | 7 | x | × | 60 | + | 7 | x | × | 5 | x |
| = | 6000 | − | 500 | x | − | 420 | x | + | 35 | x | x |
| = | 6000 | − | 920 | x | + | 35 | x | x |
| 6000 | − | 920 | x | + | 35 | x | x | = | 3600 |