| ( | x | − | 200 | ) | × | 3 5 | = | ( | x | − | 100 | ) | × | 7 10 |
| Left side of the equation = | x | × | 3 5 | − | 200 | × | 3 5 |
| = | x | × | 3 5 | − | 120 |
3 5 | x | − | 120 | = | ( | x | − | 100 | ) | × | 7 10 |
| Right side of the equation = | x | × | 7 10 | − | 100 | × | 7 10 |
| = | x | × | 7 10 | − | 70 |
3 5 | x | − | 120 | = | 7 10 | x | − | 70 |
3 5 | x | − | 7 10 | x | = | - | 70 | + | 120 |
| - | 1 10 | x | = | - | 70 | + | 120 |
| - | 1 10 | x | = | 50 |
| - | 50 | = | 1 10 | x |
1 10 | x | = | - | 50 |
| x | = | - | 50 | ÷ | 1 10 |
| = | - | 50 | × | 10 |
| x | = | - | 500 |