\(\frac{7}{9}\cdot\frac{3}{5}=\frac{7\cdot3}{9\cdot5}=\frac{7\cdot1}{3\cdot5}=\frac{7}{15}\)

\(\frac{9}{22}\cdot55=\frac{9}{22}\cdot\frac{55}{1}=\frac{9\cdot55}{22\cdot1}=\frac{9\cdot5}{2\cdot1}=\frac{45}{2}\)

\(\frac{11}{17}:\frac{33}{34}=\frac{11}{17}\cdot\frac{34}{33}=\frac{11\cdot34}{17\cdot33}=\frac{1\cdot2}{1\cdot3}=\frac{2}{3}\)

\(\dfrac{7}{9}\cdot\dfrac{3}{35}=\dfrac{7}{3\cdot3}\cdot\dfrac{3}{7\cdot5}=\dfrac{1}{15}\)

\(\dfrac{9}{22}\cdot55=\dfrac{9}{11\cdot2}\cdot11\cdot5=\dfrac{45}{2}\)

\(\dfrac{11}{17}:\dfrac{33}{34}=\dfrac{11}{17}\cdot\dfrac{34}{33}=\dfrac{11\cdot17\cdot2}{17\cdot11\cdot3}=\dfrac{2}{3}\)

7/9 x 3/35 = 1/15

9/22 x 55 = 45/2

11/17 : 33/34 = 2/3

1/15     ;      45/2       ;      2/3

a) 683\(\times\) 35=23906

    1954\(\times\) 425=830450

    2438\(\times\) 306=746028

b) \(\dfrac{7}{9}\times\dfrac{3}{35}=\dfrac{7\times3}{9\times35}=\dfrac{1}{15}\) 

\(\dfrac{9}{22}\times55=\dfrac{9\times55}{22}=\dfrac{45}{2}\) 

\(\dfrac{11}{17}:\dfrac{33}{34}=\dfrac{11}{17}\times\dfrac{34}{33}=\dfrac{11\times34}{17\times33}=\dfrac{2}{3}\) 

c) 36,66:7,8=4,7

     15,7:6,28=2,5

      27,63:0,45=61,4

d) 16 giờ 15 phút:5=3 giờ 15 phút

    14 phút 36 giây:12=1 phút 13 giây

Câu 2: 

\(\dfrac{7}{9}\cdot\dfrac{3}{35}=\dfrac{1}{5}\cdot\dfrac{1}{3}=\dfrac{1}{15}\)

\(\dfrac{9}{22}\cdot55=\dfrac{9\cdot55}{22}=\dfrac{9\cdot5}{2}=\dfrac{45}{2}\)

a,8/3

b,1/5

c,17/135

d,2/3

e,5/2

a)\(\frac{8}{3}\)

b)\(\frac{1}{5}=0,2\)

c)\(\frac{17}{135}\)

d)\(\frac{2}{3}\)

e)\(\frac{5}{2}=2,5\)

a) 21/11 x 22/17 x 68/63

= (21 x 22 x 68)/ (11 x 17 x 63)

= 8/3

b) 5/14 x 7/13 x 26/25

= (5 x 7 x 26)/(14 x 13 x 25)

= (5 x 7 x 13 x 2) / ( 7 x 2 x 13 x 5 x 5)

= 1/5

c) 7/9 x 3/35 x 17/9

= (7 x 3 x 17)/ (9 x 35 x 9 )

= 17/135

d) 11/17 : 33/34

= 11/17 x 34/33

= (11 x 34)/(17 x 33)

= (11 x 17 x 2) / ( 17 x 33 x 11)

=2/33

e) 15,7 : 6,28

= 157/10 : 157/ 25

= 157/10 x 25/157

= (157 x 25) / ( 10 x 157)

= 25/10 = 5/2

k nha

(45+75)*66+(75+45)*34

=(45+75)*(66+34)

=120*100

=12000

11+22+33+44+55+66+77+88+99:11

=11+22+33+44+55+66+77+88+9

=(11+9)+(22+88)+(33+77)+(44+66)+55

=20+110*3+55

=20+330+55

=405

Ta có :

a, (45 + 75) x 66 + (75 + 45) x 34

=  (45 + 75) x (66 + 34)

=   120  x 100

=  12000

11 + 22 + 33 + 44 + 55 + 66 + 77 + 88 + 99 : 11

= 33 + 77 + 121 + 165 + 9

= 405

\(11+22+33+44+55+66+77+88+99:11\)

\(\left(11+99\right)+\left(22+88\right)+\left(33+77\right)+\left(44+66\right)+55:11\)

\(110+110+110+110+55:11\)

\(440+55:11\)

\(445\)

\(\frac{34}{11}\cdot\frac{27}{46}\cdot\frac{23}{17}\cdot\frac{22}{9}\)

\(=\frac{34\cdot27\cdot23\cdot22}{11\cdot46\cdot17\cdot9}\)

\(=\frac{2\cdot17\cdot3\cdot3\cdot3\cdot23\cdot2\cdot11}{11\cdot2\cdot23\cdot17\cdot3\cdot3}\)

\(=\frac{3\cdot2}{1}\)

\(=6\)

=))

\(\frac{34}{11}x\frac{27}{46}x\frac{23}{17}x\frac{22}{9}\)

= 2/1 x 3/2 x 1/1 x 2/1

= 6

\(\frac{34}{11}.\frac{27}{46}.\frac{23}{17}.\frac{22}{9}\)

\(=\frac{34.27.23.22}{11.46.17.9}\)

\(=\frac{3.2}{1}=6\)

Hơi tắt chút nha, sorry !!!

11x11=121

22x22=484

33x33=1089

44x44=1936

55x55=3025

66x66=4356

k mk nhé,1000000%  đúng

11 x 11 = 121

22 x 22 = 484

33 x 33 = 1089

44 x 44 = 1936

55 x 55 = 3025

66 x 66 = 3356

11 x 11 = 121

22 x 22 = 484

33 x 33 = 1089

44 x 44 = 1936

55 x 55 = 3025

66 x 66 = 4356