| ( | 40 | − | 15 | x | ) | ( | 3 | x | ) | × | 1 | ÷ | 2 | = | 40 |
| Left side of the equation = | ( | 40 | − | 15 | x | ) | ( | 3 | x | ) | × | 1 2 |
| ( | 40 | − | 15 | x | ) | ( | 3 | x | ) | × | 1 2 | = | 40 |
| Left side of the equation = | 40 | ( | 3 | x | ) | × | 1 2 | − | 15 | x | ( | 3 | x | ) | × | 1 2 |
| = | 20 | ( | 3 | x | ) | − | 15 2 | x | ( | 3 | x | ) |
| = | 20 | × | 3 | x | − | 15 2 | x | ( | 3 | x | ) |
| = | 60 | x | − | 15 2 | x | ( | 3 | x | ) |
| = | 60 | x | − | 15 2 | x | × | 3 | x |
| = | 60 | x | − | 45 2 | x | x |
| 60 | x | − | 45 2 | x | x | = | 40 |
| x1= | 4 3 |
| x2= | 4 3 |