80 100 | x | + | 15 100 | ( | 420 | − | x | ) | = | 420 | × | 10 100 |
| Left side of the equation = | 80 100 | x | + | 15 100 | × | 420 | − | 15 100 | x |
| = | 80 100 | x | + | 63 | − | 15 100 | x |
| = | 13 20 | x | + | 63 |
13 20 | x | + | 63 | = | 420 | × | 10 100 |
| Right side of the equation = | 42 |
13 20 | x | + | 63 | = | 42 |
13 20 | x | = | 42 | − | 63 |
13 20 | x | = | - | 21 |
| x | = | - | 21 | ÷ | 13 20 |
| = | - | 21 | × | 20 13 |
| x | = | - | 420 13 |
| x | = | - 32.307692 |