| ( | 10 | + | 2 5 | x | ) | ( | 2000 | − | 5 | x | ) | − | 2000 | × | 8 | = | 30800 |
| Left side of the equation = | ( | 10 | + | 2 5 | x | ) | ( | 2000 | − | 5 | x | ) | − | 16000 |
| ( | 10 | + | 2 5 | x | ) | ( | 2000 | − | 5 | x | ) | − | 16000 | = | 30800 |
| Left side of the equation = | 10 | ( | 2000 | − | 5 | x | ) | + | 2 5 | x | ( | 2000 | − | 5 | x | ) | − | 16000 |
| = | 10 | × | 2000 | − | 10 | × | 5 | x | + | 2 5 | x | ( | 2000 | − | 5 | x | ) | − | 16000 |
| = | 20000 | − | 50 | x | + | 2 5 | x | ( | 2000 | − | 5 | x | ) | − | 16000 |
| = | 4000 | − | 50 | x | + | 2 5 | x | ( | 2000 | − | 5 | x | ) |
| = | 4000 | − | 50 | x | + | 2 5 | x | × | 2000 | − | 2 5 | x | × | 5 | x |
| = | 4000 | − | 50 | x | + | 800 | x | − | 2 | x | x |
| = | 4000 | + | 750 | x | − | 2 | x | x |
| 4000 | + | 750 | x | − | 2 | x | x | = | 30800 |