| 40 | × | 2 | X | + | 40 | X | + | 60 | ( | 1000 | − | 2 | X | − | X | ) | = | 42000 |
| Left side of the equation = | 80 | X | + | 40 | X | + | 60 | ( | 1000 | − | 2 | X | − | X | ) |
| = | 120 | X | + | 60 | ( | 1000 | − | 2 | X | − | X | ) |
| 120 | X | + | 60 | ( | 1000 | − | 2 | X | − | X | ) | = | 42000 |
| Left side of the equation = | 120 | X | + | 60 | × | 1000 | − | 60 | × | 2 | X | − | 60 | X |
| = | 120 | X | + | 60000 | − | 120 | X | − | 60 | X |
| = | - | 60 | X | + | 60000 |
| - | 60 | X | + | 60000 | = | 42000 |
| - | 60 | X | = | 42000 | − | 60000 |
| - | 60 | X | = | - | 18000 |
| 18000 | = | 60 | X |
| 60 | X | = | 18000 |
| X | = | 18000 | ÷ | 60 |
| = | 18000 | × | 1 60 |
| = | 300 | × | 1 |
| X | = | 300 |