| ( | m | − | 40 | ) | ( | 50 | + | 2 | ( | 52 | − | m | ) | ) | = | 2820 |
| Left side of the equation = | m | ( | 50 | + | 2 | ( | 52 | − | m | ) | ) | − | 40 | ( | 50 | + | 2 | ( | 52 | − | m | ) | ) |
| = | m | × | 50 | + | m | × | 2 | ( | 52 | − | m | ) | − | 40 | ( | 50 | + | 2 | ( | 52 | − | m | ) | ) |
| = | 50 | m | + | m | × | 2 | × | 52 | − | m | × | 2 | m | − | 40 | ( | 50 | + | 2 | ( | 52 | − | m | ) | ) |
| = | 50 | m | + | m | × | 104 | − | m | × | 2 | m | − | 40 | ( | 50 | + | 2 | ( | 52 | − | m | ) | ) |
| = | 154 | m | − | m | × | 2 | m | − | 40 | ( | 50 | + | 2 | ( | 52 | − | m | ) | ) |
| = | 154 | m | − | m | × | 2 | m | − | 40 | × | 50 | − | 40 | × | 2 | ( | 52 | − | m | ) |
| = | 154 | m | − | m | × | 2 | m | − | 2000 | − | 80 | ( | 52 | − | m | ) |
| = | 154 | m | − | m | × | 2 | m | − | 2000 | − | 80 | × | 52 | + | 80 | m |
| = | 154 | m | − | m | × | 2 | m | − | 2000 | − | 4160 | + | 80 | m |
| = | 234 | m | − | m | × | 2 | m | − | 6160 |
| 234 | m | − | m | × | 2 | m | − | 6160 | = | 2820 |