| ( | 440 | + | x | ) | ÷ | ( | 503 | + | x | ) | = | 9 10 |
| Multiply both sides of the equation by: | ( | 503 | + | x | ) |
| ( | 440 | + | x | ) | = | 9 10 | ( | 503 | + | x | ) |
| 440 | + | x | = | 9 10 | ( | 503 | + | x | ) |
| 440 | + | x | = | 9 10 | × | 503 | + | 9 10 | x |
| 440 | + | x | = | 4527 10 | + | 9 10 | x |
| x | − | 9 10 | x | = | 4527 10 | − | 440 |
1 10 | x | = | 4527 10 | − | 440 |
1 10 | x | = | 127 10 |
| x | = | 127 10 | ÷ | 1 10 |
| = | 127 10 | × | 10 |
| = | 127 | × | 1 |
| x | = | 127 |