| 900 | = | 6 | ÷ | ( | 1 | + | r | ) | + | 6 | ÷ | ( | 1 | + | r | ) | × | ( | 1 | + | r | ) | + | 106 | ÷ | ( | 1 | + | r | ) | × | ( | 1 | + | r | ) | ( | 1 | + | r | ) |
| Multiply both sides of the equation by: | ( | 1 | + | r | ) |
| 900 | ( | 1 | + | r | ) | = | 6 | + | 6 | ( | 1 | + | r | ) | + | 106 | ( | 1 | + | r | ) | ( | 1 | + | r | ) |
| 900 | × | 1 | + | 900 | r | = | 6 | + | 6 | ( | 1 | + | r | ) | + | 106 | ( | 1 | + | r | ) | ( | 1 | + | r | ) |
| 900 | × | 1 | + | 900 | r | = | 6 | + | 6 | × | 1 | + | 6 | r | + | 106 | ( | 1 | + | r | ) | ( | 1 | + | r | ) |
| 900 | + | 900 | r | = | 6 | + | 6 | + | 6 | r | + | 106 | ( | 1 | + | r | ) | ( | 1 | + | r | ) |
| 900 | + | 900 | r | = | 12 | + | 6 | r | + | 106 | ( | 1 | + | r | ) | ( | 1 | + | r | ) |
| 900 | + | 900 | r | = | 12 | + | 6 | r | + | 106 | × | 1 | ( | 1 | + | r | ) | + | 106 | r | ( | 1 | + | r | ) |
| 900 | + | 900 | r | = | 12 | + | 6 | r | + | 106 | ( | 1 | + | r | ) | + | 106 | r | ( | 1 | + | r | ) |
| 900 | + | 900 | r | = | 12 | + | 6 | r | + | 106 | × | 1 | + | 106 | r | + | 106 | r | ( | 1 | + | r | ) |
| 900 | + | 900 | r | = | 12 | + | 6 | r | + | 106 | + | 106 | r | + | 106 | r | ( | 1 | + | r | ) |
| 900 | + | 900 | r | = | 118 | + | 112 | r | + | 106 | r | ( | 1 | + | r | ) |
| 900 | + | 900 | r | = | 118 | + | 112 | r | + | 106 | r | × | 1 | + | 106 | r | r |
| 900 | + | 900 | r | = | 118 | + | 112 | r | + | 106 | r | + | 106 | r | r |
| 900 | + | 900 | r | = | 118 | + | 218 | r | + | 106 | r | r |