| 7 | R | ÷ | ( | 7 | + | R | ) | ÷ | 12 | + | R | = | 1 | ÷ | 2 |
| Multiply both sides of the equation by: | ( | 7 | + | R | ) |
| 7 | R | ÷ | 12 | + | R | ( | 7 | + | R | ) | = | 1 | ÷ | 2 | × | ( | 7 | + | R | ) |
| 7 | R | ÷ | 12 | + | R | × | 7 | + | R | R | = | 1 | ÷ | 2 | × | ( | 7 | + | R | ) |
| 7 | R | ÷ | 12 | + | R | × | 7 | + | R | R | = | 1 | ÷ | 2 | × | 7 | + | 1 | ÷ | 2 | × | R |
7 12 | R | + | R | × | 7 | + | R | R | = | 7 2 | + | 1 2 | R |
91 12 | R | + | R | R | = | 7 2 | + | 1 2 | R |