| ( | x | − | 9 | ) | ÷ | 4000 | × | 9 | = | ( | x | − | 12 | ) | ÷ | 2000 | × | 12 |
| Left side of the equation = | ( | x | − | 9 | ) | × | 9 4000 |
| ( | x | − | 9 | ) | × | 9 4000 | = | ( | x | − | 12 | ) | ÷ | 2000 | × | 12 |
| Left side of the equation = | x | × | 9 4000 | − | 9 | × | 9 4000 |
| = | x | × | 9 4000 | − | 81 4000 |
9 4000 | x | − | 81 4000 | = | ( | x | − | 12 | ) | ÷ | 2000 | × | 12 |
| Right side of the equation = | ( | x | − | 12 | ) | × | 3 500 |
9 4000 | x | − | 81 4000 | = | ( | x | − | 12 | ) | × | 3 500 |
| Right side of the equation = | x | × | 3 500 | − | 12 | × | 3 500 |
| = | x | × | 3 500 | − | 9 125 |
9 4000 | x | − | 81 4000 | = | 3 500 | x | − | 9 125 |
9 4000 | x | − | 3 500 | x | = | - | 9 125 | + | 81 4000 |
| - | 3 800 | x | = | - | 9 125 | + | 81 4000 |
| - | 3 800 | x | = | - | 207 4000 |
207 4000 | = | 3 800 | x |
3 800 | x | = | 207 4000 |
| x | = | 207 4000 | ÷ | 3 800 |
| = | 207 4000 | × | 800 3 |
| = | 69 5 | × | 1 |
| x | = | 69 5 |
| x | = | 13.8 |