| ( | 60 | + | 30 | x | ) | ( | 40 | − | 5 | x | ) | = | 3600 |
| Left side of the equation = | 60 | ( | 40 | − | 5 | x | ) | + | 30 | x | ( | 40 | − | 5 | x | ) |
| = | 60 | × | 40 | − | 60 | × | 5 | x | + | 30 | x | ( | 40 | − | 5 | x | ) |
| = | 2400 | − | 300 | x | + | 30 | x | ( | 40 | − | 5 | x | ) |
| = | 2400 | − | 300 | x | + | 30 | x | × | 40 | − | 30 | x | × | 5 | x |
| = | 2400 | − | 300 | x | + | 1200 | x | − | 150 | x | x |
| = | 2400 | + | 900 | x | − | 150 | x | x |
| 2400 | + | 900 | x | − | 150 | x | x | = | 3600 |