\(A=\frac{13}{28}\left(-\frac{5}{9}-\frac{4}{9}\right)=\frac{13}{28}\left(-\frac{9}{9}\right)=\frac{13}{28}\left(-1\right)\)

=> \(A=-\frac{13}{28}\)

A= -5/9x 13/28- 13/28x 4/9

  =13/28x (-5/9- 4/9)

  =13/28x (-1)

  =-13/28

ghi sai để nên mik ko giải dc

a, \(\frac{34}{13}-\frac{19}{28}-\frac{3}{31}=>\left(\frac{34}{13}-\frac{3}{31}\right)-\frac{19}{28}\)

= \(1-\frac{19}{28}=\frac{9}{28}\)

b, \(b,\frac{7}{3}-\left(\frac{11}{5}+\frac{4}{5}\right)\)

= \(\frac{7}{3}-3=>\frac{7}{3}-\frac{9}{3}=\frac{-2}{3}\)

c, \(\frac{18}{13}+\frac{55}{46}-\frac{5}{13}=\left(\frac{18}{13}-\frac{5}{13}\right)+\frac{55}{46}\)

= \(1+\frac{55}{46}=\frac{46}{46}+\frac{55}{46}=\frac{101}{46}\)

đúng nha 100%

\(\frac{4x}{28}=\frac{13}{19}+\frac{8}{15}\)

\(\frac{x}{7}=\frac{347}{285}\)

\(x=\frac{347}{285}:7\)

\(x=\frac{2429}{285}\)

\(\frac{4x}{28}=\frac{13}{19}+\frac{8}{15}\)

\(\Rightarrow\frac{4x}{28}=\frac{347}{285}\)

\(\Rightarrow4x=\frac{28.347}{285}=\frac{9716}{285}\)

\(\Rightarrow x=\frac{9716}{285}:4=\frac{2429}{285}\)

a) -30

b)\(\frac{3}{2}\)

c)\(\frac{153.\left(24-11\right)}{-153}\)=\(\frac{153.13}{-153}\)=\(\frac{13}{-1}\)= -13

Mik trả lời nhanh nè mà có đc k đâu !!!

Theo quy ước với mọi phân số lớn hơn 0 thì ta có:

\(\dfrac{a}{b}>0=>\dfrac{a}{b}< \dfrac{a+n}{b+n}\left(n\in N;n\ne0\right)\)

Áp dụng với bài trên ta => ĐPCM

CHÚC BẠN HỌC TỐT.......

1) \(\left(-1\dfrac{1}{5}+x\right):\left(-3\dfrac{3}{5}\right)=\dfrac{-7}{4}+\dfrac{1}{4}:\dfrac{1}{8}\)

\(\Leftrightarrow\left(-1\dfrac{1}{5}+x\right):\left(-3\dfrac{3}{5}\right)=\dfrac{-7}{4}+2\)

\(\Leftrightarrow\left(-1\dfrac{1}{5}+x\right):\left(-3\dfrac{3}{5}\right)=\dfrac{1}{4}\)

\(\Leftrightarrow-1\dfrac{1}{5}+x=\dfrac{1}{4}.\left(-3\dfrac{3}{5}\right)\)

\(\Leftrightarrow-1\dfrac{1}{5}+x=\dfrac{1}{4}.\left(-\dfrac{18}{5}\right)\)

\(\Leftrightarrow-1\dfrac{1}{5}+x=-\dfrac{9}{10}\)

\(\Leftrightarrow x=\left(-\dfrac{9}{10}\right)-\left(-1\dfrac{1}{5}\right)\)

\(\Leftrightarrow x=\dfrac{3}{10}\)