Vì (-0,4) : x = 1,2 : 0,3 nên \(\frac{{ - 0,4}}{x} = \frac{{1,2}}{{0,3}} \Rightarrow ( - 0,4).0,3 = 1,2.x \Rightarrow x = \frac{{( - 0,4).0,3}}{{1,2}} =  - 0,1\)

Vậy x = - 0,1

0,15 : 3\(\sqrt{x}=0,3:\frac{2}{3}\)

=> 0,15 : \(3\sqrt{x}=0,45\)

=> \(3\sqrt{x}=\frac{1}{3}\)

=>\(\sqrt{x}=\frac{1}{9}\)

=> x = \(\left(\frac{1}{9^{ }}\right)2\)

=> x = \(\frac{1}{81}\)

a) x= 1/5

b) x = 0,01

a)2,5:7,5=x:3/5

0,(3)=x:3/5

\(\Rightarrow\)x= 1/5

b)x:2,5=0,003;0,75

x:2,5=1/250

\(\Rightarrow\)x=1/100

413 :x4 =60,3 

⇒133 :x4 =20

⇒x4 =133 :20

⇒x4 =1360 

⇒x=1360 .4

⇒x=1315 

<=> 13/3 : x/4 = 20

<=> x/4 = 13/3 : 20 = 13/60

<=> x = 13/60 . 4 = 13/15

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4,5 : 0,3  =  2,25 : (0,1.x)

        15   = 2,25 : (0,1.x)

15 : 2,25  = 0,1.x

      20/3   = 0,1.x

20/3 : 0,1 = x

      200/3 = x

Ta có: 4,5 : 0,3 = 2,25 : (0,1 . x)

=> 4,5 . (0,1. x) = 2,25 . 0,3

=> 0,45 . x         = 0,675

=> x = 0,675 : 0,45

=> x = 1,5

Vậy x = 1,5

a, Ta có: x = 2,5 . 3/5 : 7,5 = 1/5

b, Ta có: x = 3 . 5 : 7 = 15/7

c, Ta có: x = -2 . 37 : 3,6 = -185/9

a) \(2.5\div7.5=x\div\frac{3}{5}\)

\(x\div\frac{3}{5}=\frac{1}{3}\)

\(x=\frac{1}{3}×\frac{3}{5}\)

\(x=\frac{3}{15}=\frac{1}{5}\)

Vậy, \(x=\frac{1}{5}\)

b) \(x\div5=3\div7\)

\(x\div5=\frac{3}{7}\)

\(x=\frac{3}{7}×5\)

\(x=\frac{15}{7}\)

Vậy, \(x=\frac{15}{7}\)

c) \(x\div37=\frac{-2}{3×6}\)

\(x\div37=\frac{-5}{9}\)

\(x=\frac{-5}{9}×37\)

\(x=\frac{-185}{9}\)

Vậy, \(x=\frac{-185}{9}\)

Cbht

a) \(\left(\frac{1}{3}.x\right):\frac{2}{3}=\frac{7}{4}:\frac{2}{5}\)

\(\left(\frac{1}{3}.x\right):\frac{2}{3}=\frac{35}{8}\)

\(\Rightarrow\frac{1}{3}.x=\frac{35}{8}.\frac{2}{3}\)

\(\Rightarrow\frac{1}{3}.x=\frac{35}{12}\)

\(\Rightarrow x=\frac{35}{12}:\frac{1}{3}\)

\(\Rightarrow x=\frac{35}{4}\)

Vậy \(x=\frac{35}{4}\)

a) x= \(\frac{35}{4}\)

\(a.\left(\frac{1}{3}.x\right):\frac{2}{3}=\frac{7}{4}:\frac{2}{5}\)

    \(\left(\frac{1}{3}.x\right):\frac{2}{3}=\frac{35}{8}\)

          \(\left(\frac{1}{3}.x\right)=\frac{35}{8}.\frac{2}{3}\)

          \(\left(\frac{1}{3}.x\right)=\frac{35}{12}\)

                    \(x=\frac{35}{12}:\frac{1}{3}\)

                    \(x=\frac{35}{4}\)

\(b.4,5:0,3=2,25:\left(0,1.x\right)\)

\(\Rightarrow2,25:\left(0,1.x\right)=4,5:0,3\)

     \(2,25:\left(0,1.x\right)=15\)

     \(2,25:\left(0,1.x\right)=2,25:15\)

                \(\left(0,1.x\right)=0,15\)

                          \(x=0,15:0,1\)

                          \(x=1,5\)

\(c.8:\left(\frac{1}{4}.x\right)=2:0,02\)

   \(8:\left(\frac{1}{4}.x\right)=100\)

        \(\left(\frac{1}{4}.x\right)=8:100\)

        \(\left(\frac{1}{4}.x\right)=\frac{2}{25}\)

                  \(x=\frac{2}{25}:\frac{1}{4}\)

                  \(x=\frac{8}{25}\)

\(d.3:\frac{9}{4}=\frac{3}{4}:\left(6.x\right)\)

\(\Rightarrow\frac{3}{4}:\left(6.x\right)=3:\frac{9}{4}\)

     \(\frac{3}{4}:\left(6.x\right)=\frac{4}{3}\)

           \(\left(6.x\right)=\frac{3}{4}:\frac{4}{3}\)

          \(\left(6.x\right)=\frac{9}{16}\)

                \(x=\frac{9}{16}:6\)

                \(x=\frac{3}{32}\)

 ^...^ ^_^