a: \(\dfrac{x}{0.9}=\dfrac{5}{6}\)

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

b: \(\dfrac{-6}{x}=\dfrac{9}{-15}\)

\(\Leftrightarrow x=10\)

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

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

4: Giá của chiếc cặp sau khi giảm là:

450000*0,75=337500 đồng

3:

thời gian đi là:

9h42'-8h30'=1h12'=1,2h

Vận tốc của xe là:

60:1,2=50km/h

2: 

a) \(\frac{x}{-4}=\frac{-3}{5}\)

\(\Rightarrow5x=\left(-3\right).\left(-4\right)\)

\(\Rightarrow5x=12\)

\(\Rightarrow x=\frac{12}{5}\)

những câu khác làm tương tự. Chỉ cần tích chéo là được

\(1\frac{1}{3}:0,8=\frac{2}{3}:x\)

\(\frac{4}{3}:\frac{4}{5}=\frac{2}{3}:x\)

\(\frac{2}{3}:x=\frac{4}{3}.\frac{5}{4}\)

\(\frac{2}{3}:x=\frac{5}{3}\)

\(x=\frac{2}{3}:\frac{5}{3}\)

\(x=\frac{2}{3}.\frac{3}{5}\)

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

vậy \(x=\frac{2}{5}\)

a, x/-4=-3/5

    x=-3/5:-4

    x= 3/20

a. \(\frac{11}{4}-\frac{3}{y}=\frac{5}{14}\)

                 \(\frac{3}{y}=\frac{11}{4}-\frac{5}{14}\)

                 \(\frac{3}{y}=\frac{67}{28}\)

=> y x 67 = 3 x 28

    y x 67 =84

         y  =\(\frac{84}{67}\)

b.Y x 0,7 - Y x 0,2 = 2,8

  Y x ( 0,7 - 0,2 )     =2,8

  Y x 0,5                 =2,8

        Y                   =5,6

a,  y= (5/14 - 11/4)/(-3)=67/84

b,  

Yx0,5=2,8=>Y=5,6

Giúp mk đi.

a, \(2,5:4x=0,5:0,2\)

\(\Rightarrow4x=\dfrac{2,5.0,2}{0,5}\)

\(\Rightarrow4x=1\Rightarrow x=\dfrac{1}{4}\)

b, \(\dfrac{1}{5}x:3=\dfrac{2}{3}:0,5\)

\(\Rightarrow\dfrac{1}{5}x=\dfrac{3.\dfrac{2}{3}}{0,5}\)

\(\Rightarrow\dfrac{1}{5}x=4\Rightarrow x=20\)

c, \(1,25:0,8=\dfrac{3}{8}:0,2x\)

\(\Rightarrow0,2x=\dfrac{0,8.\dfrac{3}{8}}{1,25}\)

\(\Rightarrow0,2x=0,24\Rightarrow x=1,2\)

Chúc bạn học tốt!!

a, \(2,5:4x=0,5:0,2\)

\(2,5:4x=2,5\)

\(4x=2,5:2,5\)

\(4x=1\)

\(x=1:4\)

\(x=\dfrac{1}{4}\)

Vậy .............

b, \(\dfrac{1}{5}x:3=\dfrac{2}{3}\)

\(\dfrac{1}{5}x=\dfrac{2}{3}.3\)

\(\dfrac{1}{5}x=2\)

\(x=2:\dfrac{1}{5}\)

\(x=10\)

Vậy .....

c, \(1,25:0,8=\dfrac{3}{8}:0,2x\)

\(1,5625=\dfrac{3}{8}:0,2x\)

\(0,2x=\dfrac{3}{8}:1,5625\)

\(0,2x=0,24\)

\(x=0,24:0,2\)

\(x=1,2\)

Vậy ...

a) \(2,5:4x=0,5:0,2\)

\(\Rightarrow2,5:4x=2,5\)

\(\Rightarrow4x=1\)

\(\Rightarrow x=0,25\)

b) \(\dfrac{1}{5}x:3=\dfrac{2}{3}:0,25\)

\(\Rightarrow\dfrac{1}{5}x:3=\dfrac{8}{3}\)

\(\Rightarrow\dfrac{1}{5}x=8\)

\(\Rightarrow x=40\)

c) \(1,25:0,8=\dfrac{3}{8}:0,2x\)

\(\Rightarrow\dfrac{3}{8}:0,2x=1,5625\)

\(\Rightarrow0,2x=0,24\)

\(\Rightarrow x=1,2\)

 a) x + x : 4 *1,6 + x : 6*3,6 = 222

\(\Rightarrow x+x\cdot0,4+x.0,6=222\)

\(\Rightarrow x.\left(1+0,4+0,6\right)=222\)

\(\Rightarrow x.2=222\)

\(\Rightarrow x=222:2=111\)

b) \(\left(x+0,2\right)+\left(x+0,4\right)+...+\left(x+1\right)=9,6\)

\(\Rightarrow\left(x+x+x+x+x\right)+\left(0,2+0,4+0,6+0,8+1\right)\) =9,6

\(\Rightarrow5.x+\left[\left(1-0,2\right):0,2+1\right].\left(1+0,2\right):2\) = 9,6

\(\Rightarrow5.x+3=9,6\)

\(\Rightarrow5.x=9,6-3=6,6\)

\(\Rightarrow x=6,6:5=1,32\)

(x+0,2)+(x+0,4)+(0,6)+(0,8)+(x+1)=9,6

5x+(0,2+0,4+0,6+0,8+1)=9,6

5x+3=9,6

5x     =9,6-3

5x      =6,6

  x      =6,6:5

  x       =1,32

a) kq = 111

b) kq = 1,32

giúp mk vs xin các bạn 

please

=(((((