Câu 1: A
Câu 2: D
Câu 3:
9/8 : (3/4 : 3/2)=1,125 : (0,75 : 1,5)=1,125 : 0,5=2,25
15/7 : 25/14 : 3/10=6/5:3/10=4
5/6×18/7 + 18/7×2/3=18/7×(5/6+2/3)=18/7×3/2=27/7
3/4+5/4×9/10=3/4+9/8=15/8
Câu 4:
CÁCH 1: (2/3 - 1/4)×1/2 = 5/12×1/2 = 5/24
CÁCH 2: (2/3 - 1/4)×1/2 = 2/3×1/2 - 1/4×1/2 = 1/3-1/8 = 5/24