| ( | 180 | + | 7 2 | ( | a | − | 60 | ) | ) | ÷ | a | = | 0 |
| Multiply both sides of the equation by: | a |
| ( | 180 | + | 7 2 | ( | a | − | 60 | ) | ) | = | 0 |
| 180 | + | 7 2 | ( | a | − | 60 | ) | = | 0 |
| 180 | + | 7 2 | a | − | 7 2 | × | 60 | = | 0 |
| 180 | + | 7 2 | a | − | 210 | = | 0 |
| - | 30 | + | 7 2 | a | = | 0 |
7 2 | a | = | 0 | + | 30 |
7 2 | a | = | 30 |
| a | = | 30 | ÷ | 7 2 |
| = | 30 | × | 2 7 |
| a | = | 60 7 |
| a | = | 8.571429 |