| ( | 60 | − | X | ) | ( | 100 | + | 10 | X | ) | = | 2240 |
| Left side of the equation = | 60 | ( | 100 | + | 10 | X | ) | − | X | ( | 100 | + | 10 | X | ) |
| = | 60 | × | 100 | + | 60 | × | 10 | X | − | X | ( | 100 | + | 10 | X | ) |
| = | 6000 | + | 600 | X | − | X | ( | 100 | + | 10 | X | ) |
| = | 6000 | + | 600 | X | − | X | × | 100 | − | X | × | 10 | X |
| = | 6000 | + | 500 | X | − | X | × | 10 | X |
| 6000 | + | 500 | X | − | X | × | 10 | X | = | 2240 |