| ( | 60 | − | 2 | x | ) | ( | 200 | + | x | ) | = | 14000 |
| Left side of the equation = | 60 | ( | 200 | + | x | ) | − | 2 | x | ( | 200 | + | x | ) |
| = | 60 | × | 200 | + | 60 | x | − | 2 | x | ( | 200 | + | x | ) |
| = | 12000 | + | 60 | x | − | 2 | x | ( | 200 | + | x | ) |
| = | 12000 | + | 60 | x | − | 2 | x | × | 200 | − | 2 | x | x |
| = | 12000 | + | 60 | x | − | 400 | x | − | 2 | x | x |
| = | 12000 | − | 340 | x | − | 2 | x | x |
| 12000 | − | 340 | x | − | 2 | x | x | = | 14000 |