| ( | 10 | − | 6 | ) | × | 200 | + | ( | 4 | − | m | ) | ( | 200 | + | 50 | m | ) | = | 1400 |
| Left side of the equation = | 10 | × | 200 | − | 6 | × | 200 | + | ( | 4 | − | m | ) | ( | 200 | + | 50 | m | ) |
| = | 2000 | − | 1200 | + | ( | 4 | − | m | ) | ( | 200 | + | 50 | m | ) |
| = | 800 | + | ( | 4 | − | m | ) | ( | 200 | + | 50 | m | ) |
| = | 800 | + | 4 | ( | 200 | + | 50 | m | ) | − | m | ( | 200 | + | 50 | m | ) |
| = | 800 | + | 4 | × | 200 | + | 4 | × | 50 | m | − | m | ( | 200 | + | 50 | m | ) |
| = | 800 | + | 800 | + | 200 | m | − | m | ( | 200 | + | 50 | m | ) |
| = | 1600 | + | 200 | m | − | m | ( | 200 | + | 50 | m | ) |
| = | 1600 | + | 200 | m | − | m | × | 200 | − | m | × | 50 | m |
| = | 1600 | + | 0 | m | − | m | × | 50 | m |
| 1600 | + | 0 | m | − | m | × | 50 | m | = | 1400 |