| 3 | x | × | 2 | x | × | 100 | + | ( | 3 | x | × | 2 | x | − | 50 | × | 40 | ) | × | 30 | = | 642000 |
| Left side of the equation = | 600 | x | x | + | ( | 3 | x | × | 2 | x | − | 50 | × | 40 | ) | × | 30 |
| 600 | x | x | + | ( | 3 | x | × | 2 | x | − | 50 | × | 40 | ) | × | 30 | = | 642000 |
| Left side of the equation = | 600 | x | x | + | 3 | x | × | 2 | x | × | 30 | − | 50 | × | 40 | × | 30 |
| = | 600 | x | x | + | 180 | x | x | − | 60000 |
| 600 | x | x | + | 180 | x | x | − | 60000 | = | 642000 |