| 4 | ÷ | ( | 4 | + | x | ) | + | 9 | ÷ | ( | 9 | + | x | ) | = | 1 |
| Multiply both sides of the equation by: | ( | 4 | + | x | ) |
| 4 | + | 9 | ÷ | ( | 9 | + | x | ) | × | ( | 4 | + | x | ) | = | 1 | ( | 4 | + | x | ) |
| 4 | + | 9 | ÷ | ( | 9 | + | x | ) | × | 4 | + | 9 | ÷ | ( | 9 | + | x | ) | × | x | = | 1 | ( | 4 | + | x | ) |
| 4 | + | 9 | ÷ | ( | 9 | + | x | ) | × | 4 | + | 9 | ÷ | ( | 9 | + | x | ) | × | x | = | 1 | × | 4 | + | 1 | x |
| 4 | + | 36 | ÷ | ( | 9 | + | x | ) | + | 9 | ÷ | ( | 9 | + | x | ) | × | x | = | 4 | + | 1 | x |
| Multiply both sides of the equation by: | ( | 9 | + | x | ) |
| 4 | ( | 9 | + | x | ) | + | 36 | + | 9 | x | = | 4 | ( | 9 | + | x | ) | + | 1 | x | ( | 9 | + | x | ) |
| 4 | × | 9 | + | 4 | x | + | 36 | + | 9 | x | = | 4 | ( | 9 | + | x | ) | + | 1 | x | ( | 9 | + | x | ) |
| 4 | × | 9 | + | 4 | x | + | 36 | + | 9 | x | = | 4 | × | 9 | + | 4 | x | + | 1 | x | ( | 9 | + | x | ) |
| 36 | + | 4 | x | + | 36 | + | 9 | x | = | 36 | + | 4 | x | + | 1 | x | ( | 9 | + | x | ) |
| 72 | + | 13 | x | = | 36 | + | 4 | x | + | 1 | x | ( | 9 | + | x | ) |
| 72 | + | 13 | x | = | 36 | + | 4 | x | + | 1 | x | × | 9 | + | 1 | x | x |
| 72 | + | 13 | x | = | 36 | + | 4 | x | + | 9 | x | + | 1 | x | x |
| 72 | + | 13 | x | = | 36 | + | 13 | x | + | 1 | x | x |