2x－½[x－½（x－1﹚]＝⅔（x－1﹚
12x-3[x-1/2(x-1)=4(x-1)
12x-3x-3/2(x-1)=4x-4
5x-3/2(x-1)=-4
10x-3x+3=-4
7x=-7
x=-1