| ( | 168 | + | x | ) | ÷ | ( | 243 | + | x | ) | = | 7 10 |
| Multiply both sides of the equation by: | ( | 243 | + | x | ) |
| ( | 168 | + | x | ) | = | 7 10 | ( | 243 | + | x | ) |
| 168 | + | x | = | 7 10 | ( | 243 | + | x | ) |
| 168 | + | x | = | 7 10 | × | 243 | + | 7 10 | x |
| 168 | + | x | = | 1701 10 | + | 7 10 | x |
| x | − | 7 10 | x | = | 1701 10 | − | 168 |
3 10 | x | = | 1701 10 | − | 168 |
3 10 | x | = | 21 10 |
| x | = | 21 10 | ÷ | 3 10 |
| = | 21 10 | × | 10 3 |
| = | 7 | × | 1 |
| x | = | 7 |