3(x²-2xy)-[3x²-2x²-2y+2(xy+y)]
=3x²-6xy-(x²+2xy+2y)
=2x²-8xy-2y
=2×﹙-½﹚²-8×﹙-½﹚×﹙-3)-2×﹙-3)
=½-12+6
=-5.5