| ( | 60 | − | x | ) | ÷ | 40 | = | ( | 100 | − | x | ) | ÷ | 80 |
| Left side of the equation = | 60 | × | 1 40 | − | x | × | 1 40 |
| = | 3 2 | − | x | × | 1 40 |
3 2 | − | 1 40 | x | = | ( | 100 | − | x | ) | ÷ | 80 |
| Right side of the equation = | 100 | × | 1 80 | − | x | × | 1 80 |
| = | 5 4 | − | x | × | 1 80 |
3 2 | − | 1 40 | x | = | 5 4 | − | 1 80 | x |
| - | 1 40 | x | + | 1 80 | x | = | 5 4 | − | 3 2 |
| - | 1 80 | x | = | 5 4 | − | 3 2 |
| - | 1 80 | x | = | - | 1 4 |
1 4 | = | 1 80 | x |
1 80 | x | = | 1 4 |
| x | = | 1 4 | ÷ | 1 80 |
| = | 1 4 | × | 80 |
| = | 1 | × | 20 |
| x | = | 20 |