a: \(-\dfrac{2}{5}+\dfrac{4}{5}x=\dfrac{3}{5}\)

=>\(\dfrac{4}{5}x=\dfrac{3}{5}+\dfrac{2}{5}=1\)

=>\(x=1:\dfrac{4}{5}=\dfrac{5}{4}\)

b; \(-\dfrac{3}{7}-\dfrac{4}{7}:x=-2\)

=>\(\dfrac{4}{7}:x+\dfrac{3}{7}=2\)

=>\(\dfrac{4}{7}:x=2-\dfrac{3}{7}=\dfrac{11}{7}\)

=>\(x=\dfrac{4}{7}:\dfrac{11}{7}=\dfrac{4}{11}\)

= \(\frac{1}{2}\)- \(\frac{2}{3}\)+ (\(\frac{3}{4}\)- \(\frac{3}{4}\)) + ( -\(\frac{4}{5}\)+ \(\frac{4}{5}\)) + ( \(\frac{5}{6}-\frac{5}{6}\)) - \(\frac{6}{7}\)

= \(\frac{1}{2}-\frac{2}{3}-0-0-0-\frac{6}{7}\)

= \(\frac{1}{2}-\frac{2}{3}-\frac{6}{7}\)

=\(\frac{21}{42}-\frac{28}{42}-\frac{36}{42}\)

= \(\frac{-43}{42}\)

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công chúa hoa anh đào nhắn linh tinh mình sẽ báo cáo

5/4-yx5/6=-1/12

5/4-y      = -1/12:5/6

5/4-y      = -1/10

y            = 5/4-(-1/10)

y            = 27/20

\(\frac{5}{4}-y.\frac{5}{6}=\frac{1}{4}-\frac{1}{3}\)

\(\Rightarrow\frac{5}{4}-y.\frac{5}{6}=-\frac{1}{12}\)

\(\Rightarrow y.\frac{5}{6}=\frac{5}{4}-\left(-\frac{1}{12}\right)\)

\(\Rightarrow y.\frac{5}{6}=\frac{5}{4}+\frac{1}{12}\)

\(\Rightarrow y.\frac{5}{6}=\frac{4}{3}\)

\(\Rightarrow y=\frac{4}{3}:\frac{5}{6}\)

\(\Rightarrow y=\frac{8}{5}\)

Vậy  \(y=\frac{8}{5}.\)

mk nhầm nha bn

4/5+6=4/5+30/5=34/5

1/2+1/3+7/12=6/12+4/12+7/12=17/12

3/4-5/12=9/12-5/12=4/12

2/3:4/3*5=1/2*5=1/2*5/1=5/2

4 - \(\dfrac{2}{5}\) = \(\dfrac{20}{5}\) - \(\dfrac{2}{5}\) = \(\dfrac{18}{5}\)

\(\dfrac{15}{4}\) - 2 = \(\dfrac{15}{4}\) - \(\dfrac{8}{4}\) = \(\dfrac{7}{4}\)

\(\dfrac{23}{6}\) - 3 = \(\dfrac{23}{6}\) - \(\dfrac{18}{6}\) = \(\dfrac{5}{6}\)

5/8 + 0,2 : |-x/4 + 2/5| = 3/2

         0,2 : |-x/4 + 2/5| = 3/2 - 5/8 

         0,2 : |-x/4 + 2/5| = 7/8

                 |-x/4 + 2/5| = 7/8 . 0,2

                 |-x/4 + 2/5| = 7/40

\(\Rightarrow\orbr{\begin{cases}-\frac{x}{4}+\frac{2}{5}=\frac{7}{40}\\-\frac{x}{4}+\frac{2}{5}=-\frac{7}{40}\end{cases}\Rightarrow\orbr{\begin{cases}-\frac{x}{4}=-\frac{9}{40}\\-\frac{x}{4}=-\frac{23}{40}\end{cases}\Rightarrow}\orbr{\begin{cases}x=\frac{9}{10}\\x=\frac{23}{10}\end{cases}}}\)

 Báo cáo sai phạm

5/8 + 0,2 : |-x/4 + 2/5| = 3/2

         0,2 : |-x/4 + 2/5| = 3/2 - 5/8 

         0,2 : |-x/4 + 2/5| = 7/8

                 |-x/4 + 2/5| = 7/8 . 0,2

                 |-x/4 + 2/5| = 7/40

⇒[

⇒[

⇒[

\(\frac{5}{8}+0,2:\left|\frac{-x}{4}+\frac{2}{5}\right|=\frac{3}{2}\)

\(\Leftrightarrow\frac{33}{40}:\left|\frac{-x}{4}+\frac{2}{5}\right|=\frac{3}{2}\)

\(\Leftrightarrow\left|\frac{-x}{4}+\frac{2}{5}\right|=\frac{33}{40}:\frac{3}{2}\)

\(\Leftrightarrow\left|\frac{-x}{4}+\frac{2}{5}\right|=\frac{11}{20}\)

\(\Leftrightarrow\hept{\begin{cases}\Leftrightarrow\frac{-x}{4}+\frac{2}{5}=-\frac{11}{20}\\\Leftrightarrow\frac{-x}{4}+\frac{2}{5}=\frac{11}{20}\end{cases}}\Leftrightarrow\hept{\begin{cases}-\frac{x}{4}=\frac{-19}{20}\\\frac{-x}{4}=\frac{3}{20}\end{cases}\Leftrightarrow}\hept{\begin{cases}-x=-3,8\\-x=0,6\end{cases}}\Leftrightarrow\hept{\begin{cases}x=3,8\\x=-0,6\end{cases}}\)

Vậy :  \(x=3,8\) hoặc \(x=-0,6\)

5-(4/7) hay là(5-4)/7 z bn

    (\(\dfrac{2}{3}\) - \(\dfrac{11}{7}\) + \(\dfrac{13}{5}\)) - (5 - \(\dfrac{4}{7}\) + \(\dfrac{6}{5}\)) - (\(\dfrac{11}{3}\) - \(\dfrac{3}{5}\))

=   \(\dfrac{2}{3}\) - \(\dfrac{11}{7}\) + \(\dfrac{13}{5}\) - 5 + \(\dfrac{4}{7}\) - \(\dfrac{6}{5}\) - \(\dfrac{11}{3}\) + \(\dfrac{3}{5}\)

=   (\(\dfrac{2}{3}\) - \(\dfrac{11}{3}\)) - (\(\dfrac{11}{7}\) - \(\dfrac{4}{7}\)) + (\(\dfrac{13}{5}\) - \(\dfrac{6}{5}\)+ \(\dfrac{3}{5}\)) 

= \(\dfrac{-9}{3}\) - \(\dfrac{7}{7}\) + (\(\dfrac{7}{5}\) + \(\dfrac{3}{5}\)) - 5

=  - 3 - 1 + 2 - 5

=  - (3 + 1)  - ( 5 - 2)

= - 4 - 3 

= - 7

c)\(\dfrac{3}{8}\times\dfrac{5}{8}+y=\dfrac{5}{4}\) 

   \(\dfrac{15}{64}+y=\dfrac{5}{4}\) 

           \(y=\dfrac{5}{4}-\dfrac{15}{64}\) 

           \(y=\dfrac{65}{64}\)

d, \(\dfrac{3}{8}+\dfrac{5}{8}\times y=\dfrac{5}{4}\) 

          \(\dfrac{5}{8}\times y=\dfrac{5}{4}-\dfrac{3}{8}\) 

          \(\dfrac{5}{8}\times y=\dfrac{7}{8}\) 

                 \(y=\dfrac{7}{8}:\dfrac{5}{8}\) 

                \(y=\dfrac{7}{5}\)

a) 3/4 x y = 9/10

y = 9/10 : 3/4

y = 6/5

b) 3/5 : y = 7/20

y = 3/5 : 7/20 

y = 12/7

e)\(\dfrac{1}{3}+\dfrac{2}{3}:x=\dfrac{5}{2}\) 

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

       \(\dfrac{2}{3}:x=\dfrac{13}{6}\) 

             \(x=\dfrac{2}{3}:\dfrac{13}{6}\) 

             \(x=\dfrac{4}{13}\)