| ( | x | − | 800 | × | 10 100 | ) | ( | 1 | − | 20 100 | ) | ÷ | 1600 | = | 0 |
| Left side of the equation = | x | ( | 1 | − | 20 100 | ) | × | 1 1600 | − | 800 | × | 10 100 | ( | 1 | − | 20 100 | ) | × | 1 1600 |
| = | x | ( | 1 | − | 20 100 | ) | × | 1 1600 | − | 1 20 | ( | 1 | − | 20 100 | ) |
| = | x | × | 1 | × | 1 1600 | − | x | × | 20 100 | × | 1 1600 | − | 1 20 | ( | 1 | − | 20 100 | ) |
| = | x | × | 1 1600 | − | x | × | 1 8000 | − | 1 20 | ( | 1 | − | 20 100 | ) |
| = | 1 2000 | x | − | 1 20 | ( | 1 | − | 20 100 | ) |
| = | 1 2000 | x | − | 1 20 | × | 1 | + | 1 20 | × | 20 100 |
| = | 1 2000 | x | − | 1 20 | + | 1 100 |
| = | 1 2000 | x | − | 1 25 |
1 2000 | x | − | 1 25 | = | 0 |
1 2000 | x | = | 0 | + | 1 25 |
1 2000 | x | = | 1 25 |
| x | = | 1 25 | ÷ | 1 2000 |
| = | 1 25 | × | 2000 |
| = | 1 | × | 80 |
| x | = | 80 |