a: =8/5-2/3=24/15-10/15=14/15

12/20-6/18=3/5-1/3=9/15-5/15=4/15

b: 18/21-12/27=6/7-7/9=54/63-49/63=5/63

8/12-20/50=2/3-2/5=10/15-6/15=4/15

\(a,\dfrac{8}{5}-\dfrac{18}{27}=\dfrac{8}{5}-\dfrac{2}{3}=\dfrac{14}{15}\\ \dfrac{12}{20}-\dfrac{6}{18}=\dfrac{3}{5}-\dfrac{1}{3}=\dfrac{4}{15}\\ b,\dfrac{18}{21}-\dfrac{12}{27}=\dfrac{6}{7}-\dfrac{4}{9}=\dfrac{26}{63}\\ \dfrac{8}{12}-\dfrac{20}{50}=\dfrac{2}{3}-\dfrac{2}{5}=\dfrac{4}{15}\)

giúp mình với mọi người ơi

\(\dfrac{8}{24}-\dfrac{5}{25}=\dfrac{1}{3}-\dfrac{1}{5}=\dfrac{5}{15}-\dfrac{3}{15}=\dfrac{2}{15}\\ \dfrac{18}{21}-\dfrac{12}{27}=\dfrac{6}{7}-\dfrac{4}{9}=\dfrac{54}{63}-\dfrac{28}{63}=\dfrac{26}{63}\)

1/3-1/5= 2/15

6/7-4/9= 26/63

\(a,\dfrac{8}{24}-\dfrac{5}{25}=\dfrac{1}{3}-\dfrac{1}{5}=\dfrac{5}{15}-\dfrac{3}{15}=\dfrac{2}{15}\)

\(b,\dfrac{18}{21}-\dfrac{12}{27}=\dfrac{6}{7}-\dfrac{4}{9}=\dfrac{26}{63}\)

a) \(\dfrac{8}{24}-\dfrac{5}{25}=\dfrac{8:8}{24:8}-\dfrac{5:5}{25:5}=\dfrac{1}{3}-\dfrac{1}{5}=\dfrac{5}{15}-\dfrac{3}{15}=\dfrac{2}{15}\)

b) \(\dfrac{18}{21}-\dfrac{12}{27}=\dfrac{18:3}{21:3}-\dfrac{12:3}{27:3}=\dfrac{6}{7}-\dfrac{4}{9}=\dfrac{54}{63}-\dfrac{28}{63}=\dfrac{26}{63}\)

\(\frac{3}{5}-\frac{5}{35}=\frac{21}{35}-\frac{5}{35}=\frac{16}{35}\)

\(\frac{18}{27}-\frac{2}{6}=\frac{1}{3}\)

\(\frac{15}{25}-\frac{3}{21}=\frac{16}{35}\)

\(\frac{24}{36}-\frac{6}{12}=\frac{1}{6}\)

tích đúng cho mk nhé

a)8/5-18/27=216/135-90/135=126/135

b)3/5-1/3=9/15-5/15=4/15(rút gọn p/s)

c)1/3-1/5=5/15-3/15=2/15

d)6/7-12/27=162/189-84/189=78/189

a) 8/5 - 18/27

= 8/5 - 2/3

= 24/15 - 10/15

= 14/15

b) 12/20 - 6/18

= 3/5 - 1/3

= 9/15 - 5/15

= 4/15

c) 8/24 - 5/25

= 1/3 - 1/5

= 5/15 - 3/15

= 2/15

d) 18/21 - 12/27

= 6/7 - 4/9

= 54/63 - 28/63

= 26/63

Lời giải:
$\frac{20}{12}+\frac{36}{18}-\frac{21}{28}=\frac{5}{3}+2-\frac{3}{4}$

$=\frac{20}{12}+\frac{24}{12}-\frac{9}{12}=\frac{20+24-9}{12}=\frac{35}{12}$

\(=\dfrac{5}{3}+2-\dfrac{3}{4}=\dfrac{5.4+2.12-3.3}{12}=\dfrac{20+24-9}{12}=\dfrac{35}{12}\)

`8/56+3/21`

`=1/7+1/7`

`=2/7`

=1/7 + 1/7 =2/7

\(\dfrac{8}{56}+\dfrac{3}{21}\)
\(=\dfrac{1}{7}+\dfrac{1}{7}\)
\(=\dfrac{2}{7}\)

12/15 = 4/5                                                 15/10 = 3/2

14/21 = 2/3                                                 70/20 = 7/2

18/12 = 3/2                                                  55/66 = 5/6

( 4/5 - 2/3 - 3/2 ) : ( 3/2 - 7/2 - 5/6 ) = -41/30 : -17/6

                                                   = 41/85

a,\(\frac{4}{6}+\frac{18}{27}=\frac{2}{3}+\frac{2}{3}=\frac{4}{3}\)

b,\(\frac{15}{25}+\frac{6}{21}=\frac{3}{5}+\frac{2}{7}=\frac{21}{35}+\frac{10}{35}=\frac{31}{35}\)

a,4/6 = 2/3 ; 18/27 = 2/3 

ta có: 2/3 + 2/3 = 4/3

b,15/25 = 3/5 ; 6/21 = 2/7

ta có: 3/5 + 2/7 = 6/2

Rút gọn 

696+6​/3132+27 

a)8/18=4/9

4/9+5/4=16/36+45/36=61/36

b)8/24=1/3

12/28=3/7

1/3+3/7=7/21+9/21=16/21

8/7+10/21=24/21+10/21=34/21

a)=8/18+5/4=4/9+5/4=61/36

b)=8/24+12/28=1/3+3/7=16/21

8/7+10/21=34/21

a=61/36;b=16/21                               

=34/21