\(\frac{13}{2}\)\(=\frac{65}{10}\)\(=6,5\)

\(\frac{11}{40}\)\(=\frac{11x25}{40x25}\)\(=\frac{275}{1000}\)\(=0,275\)

\(\frac{32}{5}\)\(=\frac{64}{10}\)\(=6,4\)

\(\frac{21}{250}\)\(=\frac{84}{1000}\)\(=0,084\)

\(\frac{1}{200}\)\(=\frac{5}{1000}\)\(=0,005\)

\(\dfrac{13}{2}=6,5=\dfrac{65}{10}\)

\(\dfrac{11}{40}=0,275=\dfrac{275}{1000}\)

\(\dfrac{32}{5}=6,4=\dfrac{64}{10}\)

\(\dfrac{21}{250}=0,084=\dfrac{84}{1000}\)

\(\dfrac{1}{200}=0,005=\dfrac{5}{1000}\)

`13/2=7,5`

`11/40=0,275`

`32/5=6,4`

`21/250=0,084`

`1/200=0,005`

Bài 1:a,  \(\dfrac{13}{2}\) = \(\dfrac{13\times5}{2\times5}\) = \(\dfrac{65}{10}\)

          b, \(\dfrac{11}{40}\) = \(\dfrac{11\times25}{40\times25}\) = \(\dfrac{275}{1000}\)

         c, \(\dfrac{21}{250}\) = \(\dfrac{21\times4}{250\times4}\) = \(\dfrac{84}{1000}\)

         d, \(\dfrac{27}{45}\) = \(\dfrac{27:9}{45:9}\) = \(\dfrac{3}{5}\) = \(\dfrac{3\times2}{5\times2}\) = \(\dfrac{6}{10}\)

Bài 2:

a, (3\(\dfrac{1}{8}\) + 1\(\dfrac{3}{4}\)): 2\(\dfrac{1}{4}\)

= (\(\dfrac{25}{8}\) + \(\dfrac{7}{4}\)): \(\dfrac{9}{4}\)

= \(\dfrac{39}{8}\) \(\times\) \(\dfrac{4}{9}\)

= \(\dfrac{13}{6}\)

b, 2\(\dfrac{5}{8}\) - 2\(\dfrac{1}{4}\) : 1\(\dfrac{1}{5}\)

=  \(\dfrac{21}{8}\) - \(\dfrac{9}{4}\): \(\dfrac{6}{5}\)

= \(\dfrac{21}{8}\) - \(\dfrac{15}{8}\)

= \(\dfrac{6}{8}\)

= \(\dfrac{3}{4}\)

1/4 = 25/100 = 0,25

5/2 = 25/10 = 2,5

13/8 = 1625/1000 = 1,625

250/500 = 500/1000 = 0,5

46/200 = 23/100 = 0,23

13/4 = 325/100 = 3,25

9/30 = 3/10 = 0,3

11/25 = 44/100 = 0,44

64/400 = 16/100 = 0,16

21/50 = 42/100 = 0,42

13/250 = 48/1000 = 0,048

Nhấn đúng cho mk nha!!!!!!!!!!!!!!

 trần duy tiến

0,3

0,44

0,16

0,42

0,052

9/30 = 3/10

11/25 = 44/100

64/400 = 16/100

21/50 = 42/100

13/250 = 52/1000

Ko biết mk lm có đúng ko???

9/30=3/10

11/25=44/100

64/400=16/100

21/50=42/100

13/250=52/1000

là sao bạn ghi rõ đi