To combine like terms in the expression:

$4 - 5 - 2x - 4y + 4 - 5x + 7y$

1. Combine the constant terms: $4 - 5 + 4 = 3$.
2. Combine the $x$-terms: $-2x - 5x = -7x$.
3. Combine the $y$-terms: $-4y + 7y = 3y$.

The simplified expression is:

$3 - 7x + 3y$

Would you like a detailed breakdown or any further clarifications? Here are 5 related questions:

1. What are like terms, and why do we combine them?
2. How would you combine terms with exponents?
3. Can you factor the expression $3 - 7x + 3y$?
4. How do you handle combining terms with multiple variables, like $x^2$ and $xy$?
5. What happens when you have terms with fractions?

Tip: When combining like terms, focus on terms that have the exact same variable and exponent.