3/4-(3/4-1/2)+5/8-(1/3-1/8)=3/4-3/4+1/2+5/8-1/3+1/8=1/2+5/8+1/8-1/3=1/2+（5/8+1/8）-1/3=2/4+3/4-1/3=5/4-1/3=15/12-4/12=11/12
