Let's evaluate the given expression step by step.

The expression is:

$\frac{4a - b}{4 - b}$

We are given that $a = 3$ and $b = 2$.

Substituting these values into the expression:

$\frac{4(3) - 2}{4 - 2}$

Simplifying the numerator:

$4(3) = 12 \quad \Rightarrow \quad 12 - 2 = 10$

Now simplify the denominator:

$4 - 2 = 2$

So, the expression becomes:

$\frac{10}{2} = 5$

Thus, the number that belongs in the green box is 5.

Would you like further details or have any questions about this solution?

Here are 5 questions to expand your understanding:

1. How does changing the values of $a$ and $b$ affect the result?
2. What happens if $b = 4$ in this expression?
3. Can you explain the importance of simplifying both the numerator and the denominator separately?
4. How would the result change if the expression were $\frac{4a + b}{4 - b}$?
5. How can you generalize this approach for more complex algebraic expressions?

Tip: Always simplify expressions step by step to avoid calculation errors, especially when dealing with multiple terms.