| x | ÷ | ( | x | + | 600 | ) | × | 100 100 | = | 40 100 |
| Multiply both sides of the equation by: | ( | x | + | 600 | ) |
| x | × | 100 100 | = | 40 100 | ( | x | + | 600 | ) |
| x | × | 100 100 | = | 40 100 | x | + | 40 100 | × | 600 |
| x | × | 100 100 | = | 40 100 | x | + | 240 |
100 100 | x | − | 40 100 | x | = | 240 |
3 5 | x | = | 240 |
| x | = | 240 | ÷ | 3 5 |
| = | 240 | × | 5 3 |
| = | 80 | × | 5 |
| x | = | 400 |