a) \(\frac{1}{5}:\frac{2}{15}=\frac{1}{5}\times\frac{15}{2}\) 

                  \(=\frac{15}{10}=\frac{3}{2}\)

b)\(\frac{3}{7}:\frac{9}{14}=\frac{3}{7}\times\frac{14}{9}\)

                \(=\frac{42}{63}=\frac{2}{3}\)

c) \(\frac{7}{12}:\frac{21}{24}=\frac{7}{12}\times\frac{24}{21}\)

                    \(=\frac{168}{252}=\frac{2}{3}\)

d) \(\frac{9}{13}:\frac{27}{26}=\frac{9}{13}\times\frac{26}{27}\)

                   \(=\frac{234}{351}=\frac{2}{3}\)

k nha

A/ 15/10 = 3/2

B/ 42/63 = 2/3

C/ 168/252 = 2/3

D/ 234/351 = 2/3

A)2/7:4/5=2/7*5/4=10/28=5/14

b)3/8:9/4=3/8*4/9=12/72=1/6

c)8/21:4/7=8/21*7/4=56/84=2/3

D)5/8:15/8=5/8*8/15=40/120=1/3

k nha

a, 5/-14. 7/-19=8/38

b, -15/4 .( 16/-25 )=12/5

c, 3/-10 .( -15/-2 )=

d, -5/7 . ( 21/-10 )=-9/4

e, 10/-3. (6/-5)==4

f, 21/-9 . ( -6/14 )=1

g, -10/9 . ( 36/20 )=-2

`a,MSC:45`

`7/9=(7xx5)/(9xx5)=35/45`

`2/5=(2xx9)/(5xx9)=18/35`

`b,MSC:21`

`6/7=(6xx3)/(7xx3)=18/21`

`17/21` giữ nguyên

`c,MSC:36`

`2/3=(2xx12)/(3xx12)=24/36`

`1/4=(1xx9)/(4xx9)=9/36`

`5/9=(5xx4)/(9xx4)=20/36`

\(a,\dfrac{7}{9}=\dfrac{7.5}{9.5}=\dfrac{35}{45}\\\dfrac{2}{5}=\dfrac{2.9}{5.9}=\dfrac{18}{45}\\ b,\dfrac{6}{7}=\dfrac{6.3}{7.3}=\dfrac{18}{21}\\ \dfrac{17}{21}giữnguyên\\ c,\dfrac{2}{3}=\dfrac{2.12}{3.12}=\dfrac{24}{36}\\ \dfrac{1}{4}=\dfrac{1.9}{4.9}=\dfrac{9}{36}\\ \dfrac{5}{9}=\dfrac{5.4}{9.4}=\dfrac{20}{36}\)

a) Ta có: \(\dfrac{-5}{7}\left(\dfrac{14}{5}-\dfrac{7}{10}\right):\left|-\dfrac{2}{3}\right|-\dfrac{3}{4}\left(\dfrac{8}{9}+\dfrac{16}{3}\right)+\dfrac{10}{3}\left(\dfrac{1}{3}+\dfrac{1}{5}\right)\)

\(=\dfrac{-5}{7}\cdot\dfrac{3}{2}\cdot\dfrac{21}{10}-\dfrac{3}{4}\cdot\dfrac{56}{3}+\dfrac{10}{3}\cdot\dfrac{8}{15}\)

\(=\dfrac{-9}{4}-14+\dfrac{16}{9}\)

\(=\dfrac{-1621}{126}\)

b) Ta có: \(\dfrac{17}{-26}\cdot\left(\dfrac{1}{6}-\dfrac{5}{3}\right):\dfrac{17}{13}-\dfrac{20}{3}\left(\dfrac{2}{5}-\dfrac{1}{4}\right)+\dfrac{2}{3}\left(\dfrac{6}{5}-\dfrac{9}{2}\right)\)

\(=\dfrac{-17}{26}\cdot\dfrac{13}{17}\cdot\dfrac{-3}{2}-\dfrac{20}{3}\cdot\dfrac{3}{20}+\dfrac{2}{3}\cdot\dfrac{-33}{10}\)

\(=\dfrac{3}{4}-1-\dfrac{11}{5}\)

\(=-\dfrac{49}{20}\)

a)  $\frac{3}{5} \times \frac{6}{7} = \frac{{3 \times 6}}{{5 \times 7}} = \frac{{18}}{{35}}$                                                 

 b) $\frac{2}{9} \times \frac{{18}}{3} = \frac{{2 \times 18}}{{9 \times 3}} = \frac{{36}}{{27}} = \frac{4}{3}$

c)  $\frac{5}{7} \times 12 = \frac{{5 \times 12}}{7} = \frac{{60}}{7}$                                            

d)  $21 \times \frac{2}{7} = \frac{{21 \times 2}}{7} = \frac{{42}}{7} = 6$

a) $\frac{5}{9}:\frac{7}{3} = \frac{5}{9} \times \frac{3}{7} = \frac{{15}}{{63}} = \frac{5}{{21}}$                                           

b) $\frac{2}{7}:\frac{8}{5} = \frac{2}{7} \times \frac{5}{8} = \frac{{10}}{{56}} = \frac{5}{{28}}$

c) $\frac{4}{{15}}:\frac{2}{5} = \frac{4}{{15}} \times \frac{5}{2} = \frac{{20}}{{30}} = \frac{2}{3}$                                         

d) $\frac{7}{9}:\frac{{21}}{9} = \frac{7}{9} \times \frac{9}{{21}} = \frac{{63}}{{189}} = \frac{1}{3}$

a) 3/5:3/4=3/5x4/3=(3x4)/(5x3)=12/15=4/5

b)2/5:3/10=2/5x10/3=(2x10)/(5x3)=20/15=4/3

c)9/8:3/4=9/8x4/3=(9x4)/(8x3)=36/32=9/8

d)1/4:1/2=1/4x2=2/4=1/2

e)1/8:1/6=1/8x6=6/8=3/4

g)1/5:1/10=1/5x10=10/5=2

a) 3/5 : 3/4 = 4/5

b) 2/5 : 3/10 = 4/3

c) 9/8 : 3/4 = 3/2

d)  1/4 : 1/2 = 1/2

e) 1/8 : 1/6 = 3/4

g) 1/5 : 1/10 = 2

tk tớ nha

a)3/5:3/4=3/5x4/3=12/15=4/5

b)2/5:3/10=2/5x10/3=20/15=5/3

c)9/8:3/4=9/8x4/3=36/24=3/2

d)1/4:1/2=1/4x2=1/2

e)1/8:1/6=1/8x6=3/4

g)1/5:1/10=1/5x10=2