7 / 4 - 5/8 = 14 / 8 - 5 / 8 = 9/8
9 / 1 . 3 / 11 = 27 / 11
1/2 . 5 / 2 = 5 / 4
\(\dfrac{7}{4}-\dfrac{5}{8}=\dfrac{14}{8}-\dfrac{5}{8}=\dfrac{9}{8}\)
\(9\times\dfrac{3}{11}=\dfrac{9\times3}{11}=\dfrac{27}{11}\)
\(\dfrac{1}{2}:\dfrac{2}{5}=\dfrac{1}{2}\times\dfrac{5}{2}=\dfrac{5}{4}\)
Bài 7: Tính
b) 7/4 - 5/8=7/4-5/8=14/8-5/8=9/8
c) 9 x 3/11=9/1.3/11=27/11
d) 1/2 : 2/5=1/2.5/2=5/4