| 40 | x | + | 1 2 | × | 40 | ( | 11 | − | x | ) | = | 360 |
| Left side of the equation = | 40 | x | + | 20 | ( | 11 | − | x | ) |
| 40 | x | + | 20 | ( | 11 | − | x | ) | = | 360 |
| Left side of the equation = | 40 | x | + | 20 | × | 11 | − | 20 | x |
| = | 40 | x | + | 220 | − | 20 | x |
| = | 20 | x | + | 220 |
| 20 | x | + | 220 | = | 360 |
| 20 | x | = | 360 | − | 220 |
| 20 | x | = | 140 |
| x | = | 140 | ÷ | 20 |
| = | 140 | × | 1 20 |
| = | 7 | × | 1 |
| x | = | 7 |