1/8-(3/8+1/4)=1/8-(3/8+2/8)=1/8-5/8=-4/8=-1/21/8-(3/8+1/4)=1/8-3/8-2/8=-4/8=-1/2
1/8-(3/8+1/4)=1/8-3/8+1/4=2/8-2/8=0
1/8-(3/8+1/4)=-1/8-3/8-1/4=-1/4-1/4=-1/2