| 5000 | ( | 1 | − | x | ) | ( | 1 | − | 4 | x | ) | = | 2400 |
| Left side of the equation = | 5000 | × | 1 | ( | 1 | − | 4 | x | ) | − | 5000 | x | ( | 1 | − | 4 | x | ) |
| = | 5000 | ( | 1 | − | 4 | x | ) | − | 5000 | x | ( | 1 | − | 4 | x | ) |
| = | 5000 | × | 1 | − | 5000 | × | 4 | x | − | 5000 | x | ( | 1 | − | 4 | x | ) |
| = | 5000 | − | 20000 | x | − | 5000 | x | ( | 1 | − | 4 | x | ) |
| = | 5000 | − | 20000 | x | − | 5000 | x | × | 1 | + | 5000 | x | × | 4 | x |
| = | 5000 | − | 20000 | x | − | 5000 | x | + | 20000 | x | x |
| = | 5000 | − | 25000 | x | + | 20000 | x | x |
| 5000 | − | 25000 | x | + | 20000 | x | x | = | 2400 |