-2分之3+1+2分之3x中括号-（-3分之1）/（-4分之1）中括号=?
-3/2+1+3/2*[-(-1/3)/(-1/4)]
=-3/2+1+3/2*[-(1/3)/(1/4)]
=-3/2+1+3/2*[-(1/3)*4]
=-3/2+1+3/2*(-4/3)
=-1/2-2
=-5/2