-0.85*17/8-18*7/2+(18除以9/7-17/9*0.85)
=-0.85*17/8-63+18*7/9-17*0.85/9
=-0.85*17(1/8+1/9)-63+14
=-17/20*17*17/72-49
=-52又593/1440
-0.85*17/8-18*7/2+(18除以9/7-17/9*0.85)
=-0.85*17/8-63+18*7/9-17*0.85/9
=-0.85*17(1/8+1/9)-63+14
=-17/20*17*17/72-49
=-52又593/1440