-1-{1-[2-0.5乘以(-3分之1)]}
问题描述：
-1-{1-[2-0.5乘以(-3分之1)]}
答
-1-{1-[2-0.5乘以(-3分之1)]}
=-1-(1-(2-1/2*(-1/3)))
=-1-(1-(2+1/6))
=-1-(1-13/6)
=-1-(-7/6)
=-1+7/6
=1/6