| ( | - | 1 10 | + | 50 | ) | ( | 400 | − | x | ) | + | ( | - | 1 5 | x | + | 60 | ) | x | = | 0 |
| Left side of the equation = | - | 1 10 | ( | 400 | − | x | ) | + | 50 | ( | 400 | − | x | ) | + | ( | - | 1 5 | x | + | 60 | ) | x |
| = | - | 1 10 | × | 400 | + | 1 10 | x | + | 50 | ( | 400 | − | x | ) | + | ( | - | 1 5 | x | + | 60 | ) | x |
| = | - | 40 | + | 1 10 | x | + | 50 | ( | 400 | − | x | ) | + | ( | - | 1 5 | x | + | 60 | ) | x |
| = | - | 40 | + | 1 10 | x | + | 50 | × | 400 | − | 50 | x | + | ( | - | 1 5 | x | + | 60 | ) | x |
| = | - | 40 | + | 1 10 | x | + | 20000 | − | 50 | x | + | ( | - | 1 5 | x | + | 60 | ) | x |
| = | 19960 | − | 499 10 | x | + | ( | - | 1 5 | x | + | 60 | ) | x |
| = | 19960 | − | 499 10 | x | − | 1 5 | x | x | + | 60 | x |
| = | 19960 | + | 101 10 | x | − | 1 5 | x | x |
| 19960 | + | 101 10 | x | − | 1 5 | x | x | = | 0 |