| 1200 | ( | 5 | − | m | ) | + | 30000 | − | 2000 | m | = | 28000 |
| Left side of the equation = | 1200 | × | 5 | − | 1200 | m | + | 30000 | − | 2000 | m |
| = | 6000 | − | 1200 | m | + | 30000 | − | 2000 | m |
| = | 36000 | − | 3200 | m |
| 36000 | − | 3200 | m | = | 28000 |
| - | 3200 | m | = | 28000 | − | 36000 |
| - | 3200 | m | = | - | 8000 |
| 8000 | = | 3200 | m |
| 3200 | m | = | 8000 |
| m | = | 8000 | ÷ | 3200 |
| = | 8000 | × | 1 3200 |
| = | 5 | × | 1 2 |
| m | = | 5 2 |
| m | = | 2.5 |