`5/39xx(7 4/5xx1 2/3+8 1/3xx7 4/5)`

`=5/39xx(39/5xx5/3+25/3xx39/5)`

`=5/39xx39/5(5/3+25/3)`

`=1xx30/3`

`=10`

10

10

a) \(\dfrac{2}{5}\cdot\dfrac{1}{7}+\dfrac{2}{5}\cdot\dfrac{5}{7}+\dfrac{2}{5}\)

\(=\dfrac{2}{5}\left(\dfrac{1}{7}+\dfrac{5}{7}+1\right)\)

\(=\dfrac{2}{5}\cdot\dfrac{13}{7}=\dfrac{26}{35}\)

b) \(\dfrac{1}{5}+\dfrac{2}{8}+\dfrac{4}{5}+\dfrac{7}{8}-\dfrac{1}{8}\)

\(=\left(\dfrac{1}{5}+\dfrac{4}{5}\right)+\left(\dfrac{2}{8}+\dfrac{7}{8}-\dfrac{1}{8}\right)\)

\(=1+1=2\)

c)\(\dfrac{24}{36}\cdot\dfrac{10}{12}\cdot36\)

\(=\dfrac{24\cdot10\cdot36}{36\cdot12}=\dfrac{12\cdot2\cdot10\cdot36}{12\cdot36}\)

\(=2\cdot10=20\)

bằng 1/2 nha

a, 24/35

b, 13/7

k cho mih

bạn này mới tham gia hoc24

\(\frac{7}{9}\times\frac{3}{5}+\frac{3}{5}\times\frac{5}{6}+\frac{3}{5}\times1\)

\(=\frac{3}{5}\times\left(\frac{7}{9}+\frac{5}{6}+1\right)\)

\(=\frac{3}{5}\times\frac{47}{18}\)

\(=\frac{47}{30}\)

 #hoktot<3# 

\(\frac{2}{5}-\frac{1}{7}+\frac{3}{5}.\frac{1}{3}=\frac{14}{35}-\frac{5}{35}+\frac{7}{35}=\frac{16}{35}\)

\(\frac{2}{5}-\frac{1}{7}+\frac{3}{5}\times\frac{1}{3}\)

\(=\frac{2}{5}-\frac{1}{7}+\frac{1}{5}\)

\(=\frac{9}{35}+\frac{1}{5}\)

\(=\frac{16}{35}\)

2/5x1/4:3/2

=2/20 : 3/2

=4/60=1/15

\(\dfrac{2}{5}\) x \(\dfrac{1}{4}:\dfrac{3}{2}=\dfrac{2}{20}:\dfrac{3}{2}=\dfrac{1}{10}:\dfrac{3}{2}=\dfrac{1}{10}\) x \(\dfrac{2}{3}=\dfrac{2}{30}\)