We are given the expression:

$a^3 - 5b + \frac{b}{ac}$

We need to substitute the values $a = -2$, $b = 6$, and $c = 3$ into this expression. Let's break it down step by step:

1. Substitute the values: $a^3 - 5b + \frac{b}{ac} = (-2)^3 - 5(6) + \frac{6}{(-2)(3)}$

2. Evaluate each term:

   • $(-2)^3 = -8$
   • $-5(6) = -30$
   • $\frac{6}{(-2)(3)} = \frac{6}{-6} = -1$

3. Combine everything: $-8 - 30 - 1 = -39$

So, the value of the expression is:

$\boxed{-39}$

Would you like more details or have any other questions?

Here are some related questions to expand your understanding:

1. What happens if $a = 0$ in the expression?
2. How would the result change if $c = -3$?
3. What would the outcome be if we added an additional $b^2$ term to the expression?
4. How can this expression be rewritten in terms of common factors of $a$ and $b$?
5. How would the evaluation change if $b = -6$ and $a = 2$?

Tip: Always apply order of operations (PEMDAS: parentheses, exponents, multiplication, division, addition, and subtraction) to simplify complex expressions.