| ( | 114 | + | a | ) | ÷ | ( | 130 | + | a | ) | = | 9 10 |
| Multiply both sides of the equation by: | ( | 130 | + | a | ) |
| ( | 114 | + | a | ) | = | 9 10 | ( | 130 | + | a | ) |
| 114 | + | a | = | 9 10 | ( | 130 | + | a | ) |
| 114 | + | a | = | 9 10 | × | 130 | + | 9 10 | a |
| 114 | + | a | = | 117 | + | 9 10 | a |
| a | − | 9 10 | a | = | 117 | − | 114 |
1 10 | a | = | 117 | − | 114 |
1 10 | a | = | 3 |
| a | = | 3 | ÷ | 1 10 |
| = | 3 | × | 10 |
| a | = | 30 |