a, \(x + 1/6 = -3/8 \)

\(x = -3/8 - 1/6\)

\(x = -13/24\)

Vậy \(x = -13/24\)

b, \(-3/7 - x = 4/5 - 2/3\)

\(-3/7 - x = 2/15\)

\(x = -3/7 - 2/15\)

\(x = -59/105.\)

Vậy \(x = -59/105\)

x+1/6=-3/8

x=-3/8-1/6

x=-13/24

-3/7-x=4/5+-2/3
-3/7-x=2/15

x=-3/7-2/15

x=-59/105

a)khi x=8 thì y=15

=> 8.15=120

Vậy hai đại lượng x và y tỉ lệ nghịch với nhau theo hệ số tỉ lệ là 120.

b) biểu diễn x theo y:

y=a/c=> y=120/8=>a=8.15

c) khi x =6

=>y=120/6

=>y=20

Khi x=10

=>y=120:10

=>y=12.

`x xx 6/7=5/14`

`=>x=5/14:6/7`

`=>x=5/14xx7/6`

`=>x=35/84`

`=>x=5/12`

Vậy `x=5/12`

__

`x:2/3=4/9`

`=>x=4/9xx2/3`

`=>x=8/27`

Vậy `x=8/27`

__

`x-1/4=3/2`

`=>x=3/2+1/4`

`=>x=6/4+1/4`

`=>x=7/4`

Vậy `x=7/4`

__

`x+4/5=8/9`

`=>x=8/9-4/5`

`=>x=40/45-36/45`

`=>x=4/45`

Vậy `x=4/45`

\(x\cdot\dfrac{6}{7}=\dfrac{5}{14}\)

\(x\)         \(=\dfrac{5}{14}:\dfrac{6}{7}\)

\(x\)           \(=\dfrac{5}{12}\)

\(x:\dfrac{2}{3}=\dfrac{4}{9}\)

\(x\)        \(=\dfrac{4}{9}\cdot\dfrac{2}{3}\)

\(x\)          \(=\dfrac{8}{27}\)

\(x-\dfrac{1}{4}=\dfrac{3}{2}\)

\(x\)          \(=\dfrac{3}{2}+\dfrac{1}{4}\)

\(x\)            \(=\dfrac{7}{4}\)

\(x+\dfrac{4}{5}=\dfrac{8}{9}\)

\(x\)          \(=\dfrac{8}{9}-\dfrac{4}{5}\)

\(x\)            \(=\dfrac{4}{45}\)

nhanh giúp mình với 

\(\Rightarrow-3x=\dfrac{6}{7}-\dfrac{30}{21}\\ \Rightarrow-3x=\dfrac{18}{21}-\dfrac{30}{21}\\\Rightarrow-3x=\dfrac{-12}{21}\\ \Rightarrow x=\dfrac{-12}{21}:3\\ \Rightarrow x=\dfrac{-12}{63}=\dfrac{-4}{21} \)

Bài 1: 

a: x/-2=-18/x

=>x²=36

=>x=6 hoặc x=-6

b: x/2+x/5=17/10

=>7/10x=17/10

hay x=17/7

\(75\%x+\frac{3}{4}x+x=30\)

\(\Leftrightarrow\left(75\%+\frac{3}{4}+1\right)x=30\)

\(\Leftrightarrow\frac{5}{2}x=30\)

\(\Leftrightarrow x=30:\frac{5}{2}\)

\(\Leftrightarrow x=12\)

đổi 75%=3/4.Ta có:

3/4xX+3/4xX+X=30

(3/4+3/4+1)xX=30

    5/2     x    X=30

                 X  = 30:5/2

                X   = 12

\(75\%\times x+\frac{3}{4}\times x+x=30\)

\(\frac{3}{4}\times x+\frac{3}{4}\times x+1\times x=30\)

\(\left(\frac{3}{4}+\frac{3}{4}+1\right)\times x=30\)

\(\frac{5}{2}\times x=30\)

\(x=30\div\frac{5}{2}\)

\(x=12\)

40

Chúc bạn may mắn

(30% + 1) x X = 52

130% x X = 52

X = 52 : 130%

X = 40

0,75 x X + 0,75 x X + X = 30

X x ( 0,75 + 0,75 + 1 ) = 30

X x 2,5 = 30

X = 30 : 2,5

X = 12

75%xX+3/4xX+X=30

<=>3/4xX+3/4xX+X=30

<=>10/4xX=30

<=>10xX=120

<=>X=120/10=12

Vậy X=12

0,75x + 0,75x = 30

0,75 . 2x = 30

2x = 40

x = 20

\(75\%\cdot x+\frac{3}{4}\cdot x+x=30\)

\(x\cdot\left(\frac{3}{4}+\frac{3}{4}+1\right)=30\)

\(x\cdot\frac{5}{2}=30\)

\(x=30\cdot\frac{2}{5}\)

\(x=12\)