| 20 | − | ( | 5 | − | 2 | x | ) | ( | 4 | − | 2 | x | ) | = | 17 | ÷ | 80 | × | 20 |
| Left side of the equation = | 20 | − | 5 | ( | 4 | − | 2 | x | ) | + | 2 | x | ( | 4 | − | 2 | x | ) |
| = | 20 | − | 5 | × | 4 | + | 5 | × | 2 | x | + | 2 | x | ( | 4 | − | 2 | x | ) |
| = | 20 | − | 20 | + | 10 | x | + | 2 | x | ( | 4 | − | 2 | x | ) |
| = | 0 | + | 10 | x | + | 2 | x | ( | 4 | − | 2 | x | ) |
| = | 0 | + | 10 | x | + | 2 | x | × | 4 | − | 2 | x | × | 2 | x |
| = | 0 | + | 10 | x | + | 8 | x | − | 4 | x | x |
| = | 0 | + | 18 | x | − | 4 | x | x |
| 0 | + | 18 | x | − | 4 | x | x | = | 17 | ÷ | 80 | × | 20 |
| Right side of the equation = | 17 4 |
| 0 | + | 18 | x | − | 4 | x | x | = | 17 4 |
| x1= | 1 4 |
| x2= | 17 4 |