| ( | 50 | x | + | 30 | ) | ( | 70 | + | x | ) | = | 6235 |
| Left side of the equation = | 50 | x | ( | 70 | + | x | ) | + | 30 | ( | 70 | + | x | ) |
| = | 50 | x | × | 70 | + | 50 | x | x | + | 30 | ( | 70 | + | x | ) |
| = | 3500 | x | + | 50 | x | x | + | 30 | ( | 70 | + | x | ) |
| = | 3500 | x | + | 50 | x | x | + | 30 | × | 70 | + | 30 | x |
| = | 3500 | x | + | 50 | x | x | + | 2100 | + | 30 | x |
| = | 3530 | x | + | 50 | x | x | + | 2100 |
| 3530 | x | + | 50 | x | x | + | 2100 | = | 6235 |