| ( | 40 | − | 1 5 | x | ) | ( | 500 | + | 10 | x | ) | = | 26250 |
| Left side of the equation = | 40 | ( | 500 | + | 10 | x | ) | − | 1 5 | x | ( | 500 | + | 10 | x | ) |
| = | 40 | × | 500 | + | 40 | × | 10 | x | − | 1 5 | x | ( | 500 | + | 10 | x | ) |
| = | 20000 | + | 400 | x | − | 1 5 | x | ( | 500 | + | 10 | x | ) |
| = | 20000 | + | 400 | x | − | 1 5 | x | × | 500 | − | 1 5 | x | × | 10 | x |
| = | 20000 | + | 400 | x | − | 100 | x | − | 2 | x | x |
| = | 20000 | + | 300 | x | − | 2 | x | x |
| 20000 | + | 300 | x | − | 2 | x | x | = | 26250 |