$\frac{a}{6}=-2$

Step 1 ：The given equation is \(\frac{a}{6}=-2\).

Step 2 ：To find the value of 'a', we need to isolate 'a' on one side of the equation. We can do this by multiplying both sides of the equation by 6.

Step 3 ：So, the value of 'a' is -12.

Step 4 ：Final Answer: \(a = \boxed{-12}\)