| ( | - | 2 | + | 220 | ) | ( | x | − | 40 | ) | = | 2400 |
| Left side of the equation = | - | 2 | ( | x | − | 40 | ) | + | 220 | ( | x | − | 40 | ) |
| = | - | 2 | x | + | 2 | × | 40 | + | 220 | ( | x | − | 40 | ) |
| = | - | 2 | x | + | 80 | + | 220 | ( | x | − | 40 | ) |
| = | - | 2 | x | + | 80 | + | 220 | x | − | 220 | × | 40 |
| = | - | 2 | x | + | 80 | + | 220 | x | − | 8800 |
| = | 218 | x | − | 8720 |
| 218 | x | − | 8720 | = | 2400 |
| 218 | x | = | 2400 | + | 8720 |
| 218 | x | = | 11120 |
| x | = | 11120 | ÷ | 218 |
| = | 11120 | × | 1 218 |
| = | 5560 | × | 1 109 |
| x | = | 5560 109 |
| x | = | 51.009174 |