| 1600 | + | ( | 80 | − | x | ) | + | 10 | ( | 80 | − | x | ) | + | 40 | ( | 600 | − | 10 | ( | 80 | − | x | ) | ) | = | 9000 |
| Left side of the equation = | 1600 | + | 80 | − | x | + | 10 | ( | 80 | − | x | ) | + | 40 | ( | 600 | − | 10 | ( | 80 | − | x | ) | ) |
| = | 1680 | − | x | + | 10 | ( | 80 | − | x | ) | + | 40 | ( | 600 | − | 10 | ( | 80 | − | x | ) | ) |
| = | 1680 | − | x | + | 10 | × | 80 | − | 10 | x | + | 40 | ( | 600 | − | 10 | ( | 80 | − | x | ) | ) |
| = | 1680 | − | x | + | 800 | − | 10 | x | + | 40 | ( | 600 | − | 10 | ( | 80 | − | x | ) | ) |
| = | 2480 | − | 11 | x | + | 40 | ( | 600 | − | 10 | ( | 80 | − | x | ) | ) |
| = | 2480 | − | 11 | x | + | 40 | × | 600 | − | 40 | × | 10 | ( | 80 | − | x | ) |
| = | 2480 | − | 11 | x | + | 24000 | − | 400 | ( | 80 | − | x | ) |
| = | 26480 | − | 11 | x | − | 400 | ( | 80 | − | x | ) |
| = | 26480 | − | 11 | x | − | 400 | × | 80 | + | 400 | x |
| = | 26480 | − | 11 | x | − | 32000 | + | 400 | x |
| = | - | 5520 | + | 389 | x |
| - | 5520 | + | 389 | x | = | 9000 |
| 389 | x | = | 9000 | + | 5520 |
| 389 | x | = | 14520 |
| x | = | 14520 | ÷ | 389 |
| = | 14520 | × | 1 389 |
| x | = | 14520 389 |
| x | = | 37.326478 |