a: \(\dfrac{x}{0.9}=\dfrac{5}{6}\)

\(\Leftrightarrow x=\dfrac{3}{4}\)

b: \(\dfrac{-6}{x}=\dfrac{9}{-15}\)

\(\Leftrightarrow x=10\)

c: \(\dfrac{\dfrac{14}{15}}{\dfrac{9}{10}}=\dfrac{x}{\dfrac{3}{7}}\)

\(\Leftrightarrow x=\dfrac{3}{7}\cdot\dfrac{14}{15}:\dfrac{9}{10}=\dfrac{2}{5}\cdot\dfrac{10}{9}=\dfrac{20}{45}=\dfrac{4}{9}\)

2/3 = 2 x 4/ 3 x 4 =8/12

8/14 = 8 : 2/ 14 : 2 =4/7

5/9 = 5 x3/ 9 x 3 =15/37

35/ 40 = 35 : 5/ 40 : 5=7/8

1/   Suy ra: -35 + 7x - 2x + 20 = 15

                5x - 15 = 15

                 5x = 30

                  x = 6

2/  Suy ra:  4x - 20 - 3x - 21 = -19

                   x - 41  = -19

                    x  = 22

3/   Suy ra:   8 - 4x + 3x - 15 = 14

                    -7 -x = 14

                      x = -7 -14

                      x = -21

4/    Suy ra:   7x - 63 - 30 + 5x = -6 + 11x

                      7x + 5x - 11x = -6 +63 + 30

                       x   =    87

5/    Suy ra:  -21x +35 + 14x - 28 = 28

                       -21x + 14x = 28 +28 - 35

                         -7x = 21

                             x= -3

6/     Suy ra:  20 - 5x + 7x - 14 = -2

                        2x   =   -8

                          x = -4

7/    Suy ra:   4x +15 -5x = 7

                      -x = -8

                        x = 8

 8/   Suy ra:   5x - 35 +30 -10x = 20

                      -5x - 5 = 20

                          -5x = 25

                            x = -5

9/    Suy ra:     35 - 7x + 5x - 10 = 15

                         -7x + 5x = 15 +10 - 35

                        -2x = -10

                          x = 5

`#` `\text{dkhanhqlv}`

`4)`

`a)3.(-5/11)`

`=-15/11`

`b)3/5+4/7 . 14/6`

`=3/5 + 4/3`

`=9/15+20/15`

`=29/15`

`c) 10/21-3/8 . 4/15`

`=10/21-1/10`

`=100/210-21/210`

`=79/100`

`d)(2/3+3/4)(5/7+5/14)`

`=(8/12+9/12)(10/14+5/14)`

`=17/12 . 15/14`

`=85/56`

`5)`

`a)x-1/2=3/10 . 5/6`

`=>x-1/2=1/4`

`=>x=1/4+1/2`

`=>x=1/4+2/4`

`=>x=3/4`

`b)x/5 = -3/14`

`=>x : 5 = -3/14`

`=>x=-3/14 . 5`

`=>x=-15/14`

`c)x+2/3=9/15 . 5/27`

`=>x+2/3=1/9`

`=>x=1/9-2/3`

`=>x=1/9-6/9`

`=>x=-5/9`

4/5 x 15/11 x 2/9 = 8/33

4/7 x 2/5 + 4/7 x 3/5 = 4/7

( 5/7 + 7/8 ) x 2 =  89/28

2/14 + 3/7 - 3/14 x 2 = 1/7 

tk mình nhé, mk nhanh nhất

4/5 x 15/11 x2/9

= 4x15x2/5x11x9

= 4x5x3x2/5x11x3x3

= 8/33

4/7x2/6+4/7x3/5

=4/7x(2/6+3/5)

=4/7x 14/15

=8/15

a = 302 / 105

b = 98/9

c= 6/5

tick nha

a=302/105

b 98 /9

c6/5

k nha và học tốt

\(\frac{9}{14}-\frac{x}{7}:\frac{5}{3}=\frac{3}{14}\Leftrightarrow\frac{9}{14}-\frac{3x}{35}=\frac{3}{14}\Leftrightarrow\frac{3x}{35}=\frac{3}{7}\Leftrightarrow3x=15\Leftrightarrow x=5\)

9/14-x/7:5/3=6/14

x/7:5/3=3/14

x/7=5/14

x=35/7

X = 35 thôi

a) x - 3/2 = 4/3 

    x = 4/3 + 3/2

    x = 8/6 + 9/6 = 17/6

b) 2/5 * x = 1/3

    x = 1/3 : 2/5

    x = 1/3 x 5/2 = 5/6

c) x - 4/9 = 3/7 : 9/14

    x - 4/9 = 2/3

    x = 2/3 + 4/9

    x = 6/9 + 4/9 = 10/9

d) 3/5 * x - 1/2 = 1/5

    3/5 * x = 1/5 + 1/2 = 7/10

    x = 7/10 : 3/5

    x = 7/10 * 5/3 = 7/6

a/\(x-\dfrac{3}{2}=\dfrac{4}{3}\)
\(x=\dfrac{4}{3}+\dfrac{3}{2}\)
\(x=\dfrac{17}{6}\)
b/\(\dfrac{2}{5}\times x=\dfrac{1}{3}\)
\(x=\dfrac{1}{3}:\dfrac{2}{5}\)
\(x=\dfrac{5}{6}\)
c/\(x-\dfrac{4}{9}=\dfrac{3}{7}:\dfrac{9}{14}\)
\(x-\dfrac{4}{9}=\dfrac{2}{3}\)
\(x=\dfrac{2}{3}+\dfrac{4}{9}\)
\(x=\dfrac{10}{9}\)
d/\(\dfrac{3}{5}\times x-\dfrac{1}{2}=\dfrac{1}{5}\)
\(\dfrac{3}{5}\times x=\dfrac{1}{5}+\dfrac{1}{2}\)
\(\dfrac{3}{5}\times x=\dfrac{7}{10}\)
\(x=\dfrac{7}{10}:\dfrac{3}{5}\)
\(x=\dfrac{7}{6}\)

a,x=\(\dfrac{17}{6}\)b,x=\(\dfrac{5}{6}\)c,x=\(\dfrac{10}{9}\)d,x=\(\dfrac{7}{6}\)