7-7/3-7/4 =7(1-1/3-1/4)=35/12=2.91又12/5+4又7/9+2又12/7=17/5+43/9+26/7=(17*9*7+43*5*7+26*5*9)/(5*9*7)=()1071+1505+1170)/315=3746/315=11.92又6/5-3/2-3/1=16/5-3/2-3=3.2-1.5-3=-1.32-7/2-7/5 =2-3.5-1.4=-2.9
