| ( | 160 | + | 2 | ( | 480 | − | x | ) | ) | = | 20000 |
| Left side of the equation = | 160 | + | 2 | ( | 480 | − | x | ) |
| = | 160 | + | 2 | × | 480 | − | 2 | x |
| = | 160 | + | 960 | − | 2 | x |
| = | 1120 | − | 2 | x |
| 1120 | − | 2 | x | = | 20000 |
| - | 2 | x | = | 20000 | − | 1120 |
| - | 2 | x | = | 18880 |
| - | 18880 | = | 2 | x |
| 2 | x | = | - | 18880 |
| x | = | - | 18880 | ÷ | 2 |
| = | - | 18880 | × | 1 2 |
| = | - | 9440 | × | 1 |
| x | = | - | 9440 |