| 1680 | ÷ | ( | 7 5 | x | ) | = | 1400 | ÷ | x | − | 10 |
| Multiply both sides of the equation by: | ( | 7 5 | x | ) |
| 1680 | = | 1400 | ÷ | 1 | × | ( | 7 5 | × | 1 | ) | − | 10 | ( | 7 5 | x | ) |
| 1680 | = | 1400 | ÷ | 1 | × | 7 5 | × | 1 | − | 10 | ( | 7 5 | x | ) |
| 1680 | = | 1960 | − | 10 | ( | 7 5 | x | ) |
| 1680 | = | 1960 | − | 10 | × | 7 5 | x |
| 1680 | = | 1960 | − | 14 | x |
| 14 | x | = | 1960 | − | 1680 |
| 14 | x | = | 280 |
| x | = | 280 | ÷ | 14 |
| = | 280 | × | 1 14 |
| = | 20 | × | 1 |
| x | = | 20 |