| ( | x | − | 40 | ) | ( | 210 | − | 10 | ( | x | − | 50 | ) | ) | = | 2200 |
| Left side of the equation = | x | ( | 210 | − | 10 | ( | x | − | 50 | ) | ) | − | 40 | ( | 210 | − | 10 | ( | x | − | 50 | ) | ) |
| = | x | × | 210 | − | x | × | 10 | ( | x | − | 50 | ) | − | 40 | ( | 210 | − | 10 | ( | x | − | 50 | ) | ) |
| = | 210 | x | − | x | × | 10 | x | + | x | × | 10 | × | 50 | − | 40 | ( | 210 | − | 10 | ( | x | − | 50 | ) | ) |
| = | 210 | x | − | x | × | 10 | x | + | x | × | 500 | − | 40 | ( | 210 | − | 10 | ( | x | − | 50 | ) | ) |
| = | 710 | x | − | x | × | 10 | x | − | 40 | ( | 210 | − | 10 | ( | x | − | 50 | ) | ) |
| = | 710 | x | − | x | × | 10 | x | − | 40 | × | 210 | + | 40 | × | 10 | ( | x | − | 50 | ) |
| = | 710 | x | − | x | × | 10 | x | − | 8400 | + | 400 | ( | x | − | 50 | ) |
| = | 710 | x | − | x | × | 10 | x | − | 8400 | + | 400 | x | − | 400 | × | 50 |
| = | 710 | x | − | x | × | 10 | x | − | 8400 | + | 400 | x | − | 20000 |
| = | 1110 | x | − | x | × | 10 | x | − | 28400 |
| 1110 | x | − | x | × | 10 | x | − | 28400 | = | 2200 |