| 20 | x | × | 80 | + | 20 | x | × | 3 4 | ( | x | − | 2 100 | x | − | 80 | ) | − | 8 | x | = | 1740 |
| Left side of the equation = | 1600 | x | + | 15 | x | ( | x | − | 2 100 | x | − | 80 | ) | − | 8 | x |
| = | 1592 | x | + | 15 | x | ( | x | − | 2 100 | x | − | 80 | ) |
| 1592 | x | + | 15 | x | ( | x | − | 2 100 | x | − | 80 | ) | = | 1740 |
| Left side of the equation = | 1592 | x | + | 15 | x | x | − | 15 | x | × | 2 100 | x | − | 15 | x | × | 80 |
| = | 1592 | x | + | 15 | x | x | − | 3 10 | x | x | − | 1200 | x |
| = | 392 | x | + | 15 | x | x | − | 3 10 | x | x |
| 392 | x | + | 15 | x | x | − | 3 10 | x | x | = | 1740 |