| 3000 | x | ( | 20 100 | + | 50 100 | + | 8 100 | ) | = | 0 |
| Left side of the equation = | 3000 | x | × | 20 100 | + | 3000 | x | × | 50 100 | + | 3000 | x | × | 8 100 |
| = | 600 | x | + | 1500 | x | + | 240 | x |
| = | 2340 | x |
| 2340 | x | = | 0 |
| x | = | 0 | ÷ | 2340 |
| = | 0 | × | 1 2340 |
| x | = | 0 |
| ( | 1 | + | A | ) | = | 0 |
| Left side of the equation = | 1 | + | A |
| 1 | + | A | = | 0 |
| A | = | 0 | − | 1 |
| A | = | - | 1 |