| ( | 1 | − | 40 100 | ) | x | + | 80 100 | ( | 1400 | − | x | ) | = | 1000 |
| Left side of the equation = | 1 | x | − | 40 100 | x | + | 80 100 | ( | 1400 | − | x | ) |
| = | 3 5 | x | + | 80 100 | ( | 1400 | − | x | ) |
| = | 3 5 | x | + | 80 100 | × | 1400 | − | 80 100 | x |
| = | 3 5 | x | + | 1120 | − | 80 100 | x |
| = | - | 1 5 | x | + | 1120 |
| - | 1 5 | x | + | 1120 | = | 1000 |
| - | 1 5 | x | = | 1000 | − | 1120 |
| - | 1 5 | x | = | - | 120 |
| 120 | = | 1 5 | x |
1 5 | x | = | 120 |
| x | = | 120 | ÷ | 1 5 |
| = | 120 | × | 5 |
| x | = | 600 |