| ( | 180 | − | 10 | x | ) | ( | 52 | + | x | − | 40 | ) | = | 2000 |
| Left side of the equation = | 180 | ( | 52 | + | x | − | 40 | ) | − | 10 | x | ( | 52 | + | x | − | 40 | ) |
| = | 180 | × | 52 | + | 180 | x | − | 180 | × | 40 | − | 10 | x | ( | 52 | + | x | − | 40 | ) |
| = | 9360 | + | 180 | x | − | 7200 | − | 10 | x | ( | 52 | + | x | − | 40 | ) |
| = | 2160 | + | 180 | x | − | 10 | x | ( | 52 | + | x | − | 40 | ) |
| = | 2160 | + | 180 | x | − | 10 | x | × | 52 | − | 10 | x | x | + | 10 | x | × | 40 |
| = | 2160 | + | 180 | x | − | 520 | x | − | 10 | x | x | + | 400 | x |
| = | 2160 | + | 60 | x | − | 10 | x | x |
| 2160 | + | 60 | x | − | 10 | x | x | = | 2000 |