| ( | x | − | 35 | ) | ( | 400 | + | 20 | ( | x | − | 58 | ) | ) | = | 8400 |
| Left side of the equation = | x | ( | 400 | + | 20 | ( | x | − | 58 | ) | ) | − | 35 | ( | 400 | + | 20 | ( | x | − | 58 | ) | ) |
| = | x | × | 400 | + | x | × | 20 | ( | x | − | 58 | ) | − | 35 | ( | 400 | + | 20 | ( | x | − | 58 | ) | ) |
| = | 400 | x | + | x | × | 20 | x | − | x | × | 20 | × | 58 | − | 35 | ( | 400 | + | 20 | ( | x | − | 58 | ) | ) |
| = | 400 | x | + | x | × | 20 | x | − | x | × | 1160 | − | 35 | ( | 400 | + | 20 | ( | x | − | 58 | ) | ) |
| = | - | 760 | x | + | x | × | 20 | x | − | 35 | ( | 400 | + | 20 | ( | x | − | 58 | ) | ) |
| = | - | 760 | x | + | x | × | 20 | x | − | 35 | × | 400 | − | 35 | × | 20 | ( | x | − | 58 | ) |
| = | - | 760 | x | + | x | × | 20 | x | − | 14000 | − | 700 | ( | x | − | 58 | ) |
| = | - | 760 | x | + | x | × | 20 | x | − | 14000 | − | 700 | x | + | 700 | × | 58 |
| = | - | 760 | x | + | x | × | 20 | x | − | 14000 | − | 700 | x | + | 40600 |
| = | - | 1460 | x | + | x | × | 20 | x | + | 26600 |
| - | 1460 | x | + | x | × | 20 | x | + | 26600 | = | 8400 |