| ( | 60 | + | x | ) | ÷ | ( | 300 | + | x | ) | = | 2 5 |
| Multiply both sides of the equation by: | ( | 300 | + | x | ) |
| ( | 60 | + | x | ) | = | 2 5 | ( | 300 | + | x | ) |
| 60 | + | x | = | 2 5 | ( | 300 | + | x | ) |
| 60 | + | x | = | 2 5 | × | 300 | + | 2 5 | x |
| 60 | + | x | = | 120 | + | 2 5 | x |
| x | − | 2 5 | x | = | 120 | − | 60 |
3 5 | x | = | 120 | − | 60 |
3 5 | x | = | 60 |
| x | = | 60 | ÷ | 3 5 |
| = | 60 | × | 5 3 |
| = | 20 | × | 5 |
| x | = | 100 |