| ( | 20 | − | 12 | − | x | ) | ( | 200 | + | 50 | x | ) | = | 1750 |
| Left side of the equation = | 20 | ( | 200 | + | 50 | x | ) | − | 12 | ( | 200 | + | 50 | x | ) | − | x | ( | 200 | + | 50 | x | ) |
| = | 20 | × | 200 | + | 20 | × | 50 | x | − | 12 | ( | 200 | + | 50 | x | ) | − | x | ( | 200 | + | 50 | x | ) |
| = | 4000 | + | 1000 | x | − | 12 | ( | 200 | + | 50 | x | ) | − | x | ( | 200 | + | 50 | x | ) |
| = | 4000 | + | 1000 | x | − | 12 | × | 200 | − | 12 | × | 50 | x | − | x | ( | 200 | + | 50 | x | ) |
| = | 4000 | + | 1000 | x | − | 2400 | − | 600 | x | − | x | ( | 200 | + | 50 | x | ) |
| = | 1600 | + | 400 | x | − | x | ( | 200 | + | 50 | x | ) |
| = | 1600 | + | 400 | x | − | x | × | 200 | − | x | × | 50 | x |
| = | 1600 | + | 200 | x | − | x | × | 50 | x |
| 1600 | + | 200 | x | − | x | × | 50 | x | = | 1750 |