Suppose that a is inversely proportional to b. If a = -3 when b = -6, find a when b = 8. Express your answer as a fraction.
1. \(a=\frac{k}{b} \)
2. \(-3=\frac{k}{-6} \)
3. \(k=18\)
4. \(a=\frac{18}{8}\)