| 3000 | ( | 1 | − | m | ) | + | 200 | ( | 1 | + | 2 | m | ) | ( | 1 | − | m | ) | = | 7000 |
| Left side of the equation = | 3000 | × | 1 | − | 3000 | m | + | 200 | ( | 1 | + | 2 | m | ) | ( | 1 | − | m | ) |
| = | 3000 | − | 3000 | m | + | 200 | ( | 1 | + | 2 | m | ) | ( | 1 | − | m | ) |
| = | 3000 | − | 3000 | m | + | 200 | × | 1 | ( | 1 | − | m | ) | + | 200 | × | 2 | m | ( | 1 | − | m | ) |
| = | 3000 | − | 3000 | m | + | 200 | ( | 1 | − | m | ) | + | 400 | m | ( | 1 | − | m | ) |
| = | 3000 | − | 3000 | m | + | 200 | × | 1 | − | 200 | m | + | 400 | m | ( | 1 | − | m | ) |
| = | 3000 | − | 3000 | m | + | 200 | − | 200 | m | + | 400 | m | ( | 1 | − | m | ) |
| = | 3200 | − | 3200 | m | + | 400 | m | ( | 1 | − | m | ) |
| = | 3200 | − | 3200 | m | + | 400 | m | × | 1 | − | 400 | m | m |
| = | 3200 | − | 3200 | m | + | 400 | m | − | 400 | m | m |
| = | 3200 | − | 2800 | m | − | 400 | m | m |
| 3200 | − | 2800 | m | − | 400 | m | m | = | 7000 |