| ( | r | + | 40 | ) | ÷ | ( | r | + | 16 | ) | = | 5 | ÷ | 3 |
| Multiply both sides of the equation by: | ( | r | + | 16 | ) |
| ( | r | + | 40 | ) | = | 5 | ÷ | 3 | × | ( | r | + | 16 | ) |
| r | + | 40 | = | 5 | ÷ | 3 | × | ( | r | + | 16 | ) |
| r | + | 40 | = | 5 | ÷ | 3 | × | r | + | 5 | ÷ | 3 | × | 16 |
| r | + | 40 | = | 5 3 | r | + | 80 3 |
| r | − | 5 3 | r | = | 80 3 | − | 40 |
| - | 2 3 | r | = | 80 3 | − | 40 |
| - | 2 3 | r | = | - | 40 3 |
40 3 | = | 2 3 | r |
2 3 | r | = | 40 3 |
| r | = | 40 3 | ÷ | 2 3 |
| = | 40 3 | × | 3 2 |
| = | 20 | × | 1 |
| r | = | 20 |