1. **State the problem:** Simplify the expression $3x - [(y - x) - (x - y)]$. 2. **Recall the rules:** When subtracting expressions inside brackets, distribute the minus sign to each term inside the bracket. 3. **Simplify inside the brackets:** $$ (y - x) - (x - y) = (y - x) - x + y = y - x - x + y $$ 4. **Combine like terms inside the brackets:** $$ y - x - x + y = (y + y) - (x + x) = 2y - 2x $$ 5. **Rewrite the original expression:** $$ 3x - [2y - 2x] $$ 6. **Distribute the minus sign:** $$ 3x - 2y + 2x $$ 7. **Combine like terms:** $$ 3x + 2x - 2y = 5x - 2y $$ **Final answer:** $$ 5x - 2y $$