The given expression is $2x - y - 2y + x$. Let's simplify and solve for $x = 3$ and $y = 4$:

1. Combine like terms: $2x + x - y - 2y = 3x - 3y$

2. Substitute $x = 3$ and $y = 4$ into the expression: $3(3) - 3(4) = 9 - 12 = -3$

Final Answer: $-3$

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Related Questions:

1. What happens if $x = 0$ and $y = 0$ in the same expression?
2. How would you generalize this expression for any $x$ and $y$?
3. What is the result if $x$ and $y$ are replaced by their negatives?
4. How would this change if the coefficients of $x$ and $y$ were altered?
5. What geometric interpretation can this expression have if plotted in a coordinate system?

Tip: Always simplify expressions first to reduce calculation complexity.