23/4-(5/2÷13/4)
=23/4-(5/2×4/13)
=23/4-10/13
=259/52
(7/8-5/6)÷(7/12-1/4) 上下同乘以2
=(7/4-5/3)÷(7/6-1/2)
=(7/4-5/3)÷2/3
=(7/4-5/3)×3/2
=21/8-5/2
=1/823/4-(5/2+13/4)23/4-(5/2+13/4)=23/4-13/4-5/2=5/2-5/2=0 (2/3+5/7-1/2)÷1/42=(2/3+5/7-1/2)×42=2/3×42+5/7×42-1/2×42=28+30-21=37 10/27×9/8-(3/5-7/20)=5/12-1/4=1/6 (1/2-1/3-1/5)×60=1/2×60-1/3×60-1/5×60=30-20-12=-2 41.3×18+7.7×18+18=18(41.3+7.7+1)=18×50=900