Let's simplify the given expression:

$(2x - 3y) - (8x + 6y + 4)$

Step 1: Distribute the negative sign through the second set of parentheses:

$(2x - 3y) - 8x - 6y - 4$

Step 2: Combine like terms:

• Combine the $x$-terms: $2x - 8x = -6x$
• Combine the $y$-terms: $-3y - 6y = -9y$
• The constant term is $-4$

Final expression:

$-6x - 9y - 4$

This is the simplified form of the expression.

Do you want more details, or do you have any questions?

Here are five related questions:

1. What would happen if you substituted values for $x$ and $y$?
2. How would you simplify an expression with more variables?
3. Can you solve an equation involving this expression?
4. How do you factor expressions like $-6x - 9y$?
5. How do you handle absolute value in algebraic expressions?

Tip: Always distribute negative signs carefully to avoid mistakes when simplifying expressions.