| ( | 750 | + | x | ) | ÷ | ( | 600 | + | x | ) | = | 6 5 |
| Multiply both sides of the equation by: | ( | 600 | + | x | ) |
| ( | 750 | + | x | ) | = | 6 5 | ( | 600 | + | x | ) |
| 750 | + | x | = | 6 5 | ( | 600 | + | x | ) |
| 750 | + | x | = | 6 5 | × | 600 | + | 6 5 | x |
| 750 | + | x | = | 720 | + | 6 5 | x |
| x | − | 6 5 | x | = | 720 | − | 750 |
| - | 1 5 | x | = | 720 | − | 750 |
| - | 1 5 | x | = | - | 30 |
| 30 | = | 1 5 | x |
1 5 | x | = | 30 |
| x | = | 30 | ÷ | 1 5 |
| = | 30 | × | 5 |
| x | = | 150 |