To simplify the expression:

$\frac{4x - 4y}{y - x}$

First, factor the numerator and denominator if possible.

1. Factor the numerator $4x - 4y$: $4x - 4y = 4(x - y)$

2. Rewrite the denominator $y - x$ as $-(x - y)$: $y - x = -(x - y)$

Now substitute these factored forms back into the expression: $\frac{4(x - y)}{-(x - y)}$

The $(x - y)$ terms cancel out, leaving: $\frac{4}{-1} = -4$

Thus, the simplified expression is: $\boxed{-4}$

Would you like further details or have any questions?

Here are 5 related questions:

1. How do you factor common terms in an algebraic expression?
2. What happens when you divide two terms that are opposites?
3. Can you simplify $\frac{x^2 - y^2}{y - x}$?
4. How do you handle negative signs in fractions?
5. What are other methods of simplifying expressions involving variables?

Tip: Always look for common factors or patterns when simplifying algebraic expressions.