1/3+1/2+1/4）×12 =1/3*12+1/2*12+1/4*12=4+6+3=13378-（178+98）=378-178-98=200-98=1028/5÷2.5-1.2×1/4=0.64-0.3=0.345/3×1/4÷5/2+17/4 =5/3x1/4x2/5+17/4=1/6+17/4=53/12144×99+143 =144x99+144-1=(99+1)x1...