20 100 | + | ( | 1 | − | 20 100 | ) | ( | 320 | − | x | ) | = | 320 | × | 40 100 |
| Left side of the equation = | 20 100 | + | 1 | ( | 320 | − | x | ) | − | 20 100 | ( | 320 | − | x | ) |
| = | 20 100 | + | 1 | × | 320 | − | 1 | x | − | 20 100 | ( | 320 | − | x | ) |
| = | 20 100 | + | 320 | − | 1 | x | − | 20 100 | ( | 320 | − | x | ) |
| = | 1601 5 | − | 1 | x | − | 20 100 | ( | 320 | − | x | ) |
| = | 1601 5 | − | 1 | x | − | 20 100 | × | 320 | + | 20 100 | x |
| = | 1601 5 | − | 1 | x | − | 64 | + | 20 100 | x |
| = | 1281 5 | − | 4 5 | x |
1281 5 | − | 4 5 | x | = | 320 | × | 40 100 |
| Right side of the equation = | 128 |
1281 5 | − | 4 5 | x | = | 128 |
| - | 4 5 | x | = | 128 | − | 1281 5 |
| - | 4 5 | x | = | - | 641 5 |
641 5 | = | 4 5 | x |
4 5 | x | = | 641 5 |
| x | = | 641 5 | ÷ | 4 5 |
| = | 641 5 | × | 5 4 |
| = | 641 | × | 1 4 |
| x | = | 641 4 |
| x | = | 160.25 |