-4分之1+6分之5+3分旅链之2-2分之1 =-1/4+5/6+2/3-1/2=-1/4-1/2+5/6+2/3=-3/4+3/2=3/412-(拆冲孙-18)+(-7)-15 =12+18-7-15=30-22=84.7-(-8.9)判李-7.5+(-6) =4.7+8.9-7.5-6=4.6+9-13.5=13.6-13.5=0.1