20 100 | ( | 100 | × | 10000 | + | 900000 | ) | = | A | × | 10000 | − | A | × | 10000 | × | 5 100 | − | 1900000 |
| Left side of the equation = | 20 100 | × | 100 | × | 10000 | + | 20 100 | × | 900000 |
| = | 200000 | + | 180000 |
| = | 380000 |
| 380000 | = | A | × | 10000 | − | A | × | 10000 | × | 5 100 | − | 1900000 |
| Right side of the equation = | A | × | 10000 | − | A | × | 500 | − | 1900000 |
| = | 9500 | A | − | 1900000 |
| 380000 | = | 9500 | A | − | 1900000 |
| - | 9500 | A | = | - | 1900000 | − | 380000 |
| - | 9500 | A | = | - | 2280000 |
| 2280000 | = | 9500 | A |
| 9500 | A | = | 2280000 |
| A | = | 2280000 | ÷ | 9500 |
| = | 2280000 | × | 1 9500 |
| = | 240 | × | 1 |
| A | = | 240 |