Phép trừ phân số (tiếp theo)

`19/8 -5/4 = 19/8 - 10/8=` \(\dfrac{19-10}{8}=\dfrac{9}{8}\)

\(\dfrac{19}{8}-\dfrac{5}{4}\\ =\dfrac{19}{8}-\dfrac{10}{8}\\ =\dfrac{9}{8}\)

=32/72-135/72=-103/72

`2-5/7=14/7-5/7=9/7`

`13/7-7/7`

`=(13-7)/7`

`=6/7`

\(\dfrac{13}{7}-\dfrac{7}{7}\\ =\dfrac{13-7}{7}\\ =\dfrac{6}{7}.\)

\(\dfrac{13}{7}-\dfrac{7}{7}=\dfrac{6}{7}\)

\(\dfrac{31}{5}-\dfrac{2}{7}=\dfrac{217}{35}-\dfrac{10}{35}=\dfrac{207}{35}\)

207/35

\(=\dfrac{217}{35}-\dfrac{10}{35}=\dfrac{207}{35}\)

12/5

\(3-\dfrac{3}{5}=\dfrac{3}{1}-\dfrac{3}{5}=\dfrac{15}{5}-\dfrac{3}{5}=\dfrac{12}{5}\)

27/28

27/28

27/28

24m chiếm:

1-2/5=3/5(tấm vải)

Lúc đầu tấm vải dài:

24:3/5=40(m)