| ( | x | − | 30 | ) | ( | 100 | + | ( | 40 | − | x | ) | × | 5 | ) | = | 2500 |
| Left side of the equation = | x | ( | 100 | + | ( | 40 | − | x | ) | × | 5 | ) | − | 30 | ( | 100 | + | ( | 40 | − | x | ) | × | 5 | ) |
| = | x | × | 100 | + | x | ( | 40 | − | x | ) | × | 5 | − | 30 | ( | 100 | + | ( | 40 | − | x | ) | × | 5 | ) |
| = | 100 | x | + | x | × | 40 | × | 5 | − | x | x | × | 5 | − | 30 | ( | 100 | + | ( | 40 | − | x | ) | × | 5 | ) |
| = | 100 | x | + | x | × | 200 | − | x | x | × | 5 | − | 30 | ( | 100 | + | ( | 40 | − | x | ) | × | 5 | ) |
| = | 300 | x | − | x | x | × | 5 | − | 30 | ( | 100 | + | ( | 40 | − | x | ) | × | 5 | ) |
| = | 300 | x | − | x | x | × | 5 | − | 30 | × | 100 | − | 30 | ( | 40 | − | x | ) | × | 5 |
| = | 300 | x | − | x | x | × | 5 | − | 3000 | − | 150 | ( | 40 | − | x | ) |
| = | 300 | x | − | x | x | × | 5 | − | 3000 | − | 150 | × | 40 | + | 150 | x |
| = | 300 | x | − | x | x | × | 5 | − | 3000 | − | 6000 | + | 150 | x |
| = | 450 | x | − | x | x | × | 5 | − | 9000 |
| 450 | x | − | x | x | × | 5 | − | 9000 | = | 2500 |