`a, 3/4 + 1/2 xx 7/2`

`= 3/4 + 7/4`

`=10/4`

`=5/2`

`b, 6/15 - 1/3 : 5/3`

`= 6/15 - 1/3 xx 3/5`

`= 6/15 - 3/15`

`= 3/15`

`=1/5`

`c, x-4/9 = 3/7 : 9/4`

`=> x-4/9= 3/7 xx 4/9`

`=> x-4/9= 12/63`

`=> x-4/9=4/21`

`=> x= 4/21 +4/9`

`=>x= 40/63`

`d, 7/9 xx 3/5 -1/2=1/5`

`->` sao lại bằng có `x` ko vậy ạ?

`a,`

`3/4+1/2 \times 7/2=3/4+7/4=10/4=5/2`

`b,`

`6/15 - 1/3 \div 5/3=6/15-1/5=1/5`

`c,` Tìm x?

`x-4/9=3/7 \div 9/4`

`x-4/9=4/21`

`x=4/21+4/9`

`x=40/63`

`d, 7/9x \times 3/5-1/2=1/5`

`7/9x \times 3/5=1/5+1/2`

`7/9x \times 3/5=7/10`

`7/9x=7/10 \div 3/5`

`7/9x=7/6`

`x=7/6 \div 7/9=3/2`

Ta có: \(\left(3\dfrac{3}{4}+\dfrac{4}{7}\cdot\dfrac{7}{16}\right):\dfrac{1}{2}\)

\(=\left(\dfrac{15}{4}+\dfrac{1}{4}\right)\cdot2\)

\(=4\cdot2=8\)

Ta có:\(\left(3\dfrac{3}{4}+\dfrac{4}{7}.\dfrac{7}{16}\right):\dfrac{1}{2}\)

       \(=\left(\dfrac{15}{4}+\dfrac{1}{4}\right).2\)

       \(=\dfrac{16}{4}.2\)

       \(=8\)

= 4 : 1/2 = 4 nhân 2/1  = 8

đáp án = 8

= 4 : 1/2 = 4 nhân 2/1  = 8

đáp án = 8

101/28

43/90

3/4:1/5-1/7

=15/4-1/7

=101/28

7/9-3/5.1/2

=7/9-3/10

=43/90

3/4 : 1/5 - 1/7

=> 3/4 x 5/1 - 1/7

=> 15/4 - 1/7

=> 105/28 - 4/28

=> 101/28

7/9 - 3/5 x 1/2

=> 7/9 - 3/10

=> 70/90 - 27/90

=> 43/90

a) (2/5 x 25/29) + (3/5 x 25/29)
= (50/145) + (75/145)
= 125/145

b) (5/2 x 3/7) - (3/14 : 6/7)
= 15/14 - (3/14 x 7/6)
= 15/14 - 1/2
= (30/28) - (14/28)
= 16/28
= 4/7

c) (15/4 : 5/12) - (6/5 : 11/15)
= (15/4 x 12/5) - (6/5 x 15/11)
= 180/20 - 90/55
= 9 - 18/11
= (99/11) - (18/11)
= 81/11
= 7 4/11

a) (2/3) + (20/21 x 3/2 x 7/5)
= 2/3 + (60/210)
= 2/3 + 2/7
= (14/21) + (6/21)
= 20/21

b) (5/17 x 21/32 x 47/24 x 0)
= 0

c) (11/3 x 26/7) - (26/7 x 8/3)
= (286/21) - (208/21)
= 78/21
= 3 9/21
= 3 3/7

a) (25/8) : x = 5/16
=> (25/8) x (16/5) = x
=> 4 = x

b) x + (7/15) = 6/15
=> x = (6/15) - (7/15)
=> x = -1/15

c) x : (28/49) = 7/12
=> x x (49/28) = 7/12
=> x = (7/12) x (28/49)
=> x = 1/2

a) 6 x x = (5/8) : (3/4)
=> 6x = (5/8) x (4/3)
=> 6x = 20/24
=> 6x = 5/6
=> x = (5/6) / 6
=> x = 5/36

câu,b,không,đủ,thông,tin,nhan,bạn.

\(=\dfrac{3}{5}+\dfrac{8}{15}:\dfrac{2}{7}=\dfrac{3}{5}+\dfrac{28}{15}=\dfrac{9}{15}+\dfrac{28}{15}=\dfrac{37}{15}\)

\(=\dfrac{7}{8}+\dfrac{7}{3}-\dfrac{11}{12}=\dfrac{77}{24}-\dfrac{11}{12}=\dfrac{55}{24}\)

\(\dfrac{1}{3}\cdot\dfrac{1}{4}+\dfrac{7}{4}:3-\dfrac{2}{3}\)

\(=\dfrac{1}{12}+\dfrac{7}{12}-\dfrac{8}{12}\)

\(=\dfrac{0}{12}=0\)

a: \(x:5=\dfrac{15}{14}\\ \Rightarrow x=\dfrac{15}{70}=\dfrac{3}{14}\)

a) \(x:5=\dfrac{4}{7}+\dfrac{1}{2}\)

\(\dfrac{x}{5}=\dfrac{15}{14}\)

\(\Rightarrow x=\dfrac{5.15}{14}=\dfrac{75}{14}\)

b) \(\dfrac{1}{3}+\dfrac{2}{9}\times\dfrac{3}{4}=\dfrac{1}{3}+\dfrac{1}{6}=\dfrac{2}{6}+\dfrac{1}{6}=\dfrac{3}{6}=\dfrac{1}{2}\)

\(x\div5=\dfrac{4}{7}+\dfrac{1}{2}\)

\(x\div5=\dfrac{15}{14}\)

\(x=\dfrac{15}{14}\times5\)

\(x=\dfrac{75}{14}\)

b)

\(\dfrac{1}{3}+\dfrac{2}{9}\times\dfrac{3}{4}\)

\(=\dfrac{1}{3}+\dfrac{1}{6}\)

\(=\dfrac{1}{2}\)

Bài 1: 

a: x+1/2=5/6

nên x=5/6-1/2=1/3

b: x+1/4=3/4

nên x=3/4-1/4=2/4=1/2

c: x+3/10=1/2

nên x=1/2-3/10=5/10-3/10=1/5

d: x+1/4=3/8

nên x=3/8-1/4=3/8-2/8=1/8

TOT LAM