| 2000 | = | ( | x | − | 40 | ) | ( | 600 | − | 10 | x | ) |
| Right side of the equation = | x | ( | 600 | − | 10 | x | ) | − | 40 | ( | 600 | − | 10 | x | ) |
| = | x | × | 600 | − | x | × | 10 | x | − | 40 | ( | 600 | − | 10 | x | ) |
| = | 600 | x | − | x | × | 10 | x | − | 40 | × | 600 | + | 40 | × | 10 | x |
| = | 600 | x | − | x | × | 10 | x | − | 24000 | + | 400 | x |
| = | 1000 | x | − | x | × | 10 | x | − | 24000 |
| 2000 | = | 1000 | x | − | x | × | 10 | x | − | 24000 |