9 - $\dfrac{7}{4}$ - $\dfrac{5}{4}$
= 9 - ( $\dfrac{7}{4}$ + $\dfrac{5}{4}$ ) 
= 9 - 3
= 6
b, $\dfrac{1}{2}$ : $\dfrac{1}{5}$ + $\dfrac{1}{3}$ : $\dfrac{1}{5}$ + $\dfrac{1}{6}$ : $\dfrac{1}{5}$
= $\dfrac{1}{5}$ : ( $\dfrac{1}{2}$ + $\dfrac{1}{3}$ + $\dfrac{1}{6}$ )
= $\dfrac{1}{5}$ : 1
= $\dfrac{1}{5}$
c, $\dfrac{1}{6}$ $\times$  $\dfrac{4}{11}$ + $\dfrac{3}{4}$ $\times$  $\dfrac{4}{11}$
= $\dfrac{4}{11}$ $\times$ ( $\dfrac{1}{6}$ + $\dfrac{3}{4}$ )
= $\dfrac{4}{11}$ $\times$ $\dfrac{11}{12}$
= $\dfrac{1}{3}$
d, Không hiểu đề bài ?
e, $\dfrac{17}{24}$ - $\dfrac{1}{3}$ + $\dfrac{3}{24}$
=  $\dfrac{17}{24}$ - $\dfrac{8}{24}$ + $\dfrac{3}{24}$
= $\dfrac{1}{2}$
f, ( $\dfrac{8}{9}$ - $\dfrac{5}{6}$ ) $\times$ 4
= $\dfrac{1}{18}$ $\times$ 4
= $\dfrac{4}{18}$ = $\dfrac{2}{9}$
g, ( $\dfrac{6}{7}$ + $\dfrac{4}{5}$ ) × $\dfrac{5}{6}$
= $\dfrac{58}{35}$ × $\dfrac{5}{6}$
= $\dfrac{29}{21}$
h, $\dfrac{21}{23}$ + $\dfrac{4}{5}$ : $\dfrac{6}{8}$
= $\dfrac{21}{23}$ + $\dfrac{4}{5}$ × $\dfrac{4}{3}$
= $\dfrac{21}{23}$ + $\dfrac{16}{15}$
= $\dfrac{683}{345}$
i,  $\dfrac{5}{8}$ × $\dfrac{4}{9}$ : $\dfrac{2}{3}$
= $\dfrac{5}{12}$ : $\dfrac{2}{13}$
= $\dfrac{65}{24}$
$\text{@Meii}$

Đáp án:

Giải thích các bước giải:

 9-7/4-5/4=9-(7+5/4)=9-12/4=9-3=6

1/2:1/5+1/3:1/5+1/6:1/5=1/5:(1/2+1/3+1/6)=1/5:1=1/5

1/6x4/11+3/4x4/11=4/11×(1/6+1/4)=4/11×5/12=20/132=10/66=5/33

9/10x27x14/10/9 ??? cần ghi rõ đề bài 

17/24-1/3+3/24=17/24-8/24+3/24=17-8+3/24=8/24=1/3

(8/9-5/6)x4=1/18×4=4/18=2/9

(6/7+4/5)x5/6=58/35×5/6=29/21

21/23+4/5:6/8=21/23×16/15

5/8x4/9:2/3=5/8×4/9×3/2=60/144=15/36=5/12

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