| x | ( | 1 | + | 5 100 | ) | ÷ | ( | 15 100 | − | 5 100 | ) | = | 21 2 |
| Multiply both sides of the equation by: | ( | 15 100 | − | 5 100 | ) |
| x | ( | 1 | + | 5 100 | ) | = | 21 2 | ( | 15 100 | − | 5 100 | ) |
| x | × | 1 | + | x | × | 5 100 | = | 21 2 | ( | 15 100 | − | 5 100 | ) |
| x | × | 1 | + | x | × | 5 100 | = | 21 2 | × | 15 100 | − | 21 2 | × | 5 100 |
| x | × | 1 | + | x | × | 5 100 | = | 63 40 | − | 21 40 |
21 20 | x | = | 21 20 |
| x | = | 21 20 | ÷ | 21 20 |
| = | 21 20 | × | 20 21 |
| = | 1 | × | 1 |
| x | = | 1 |