a ) 

\(\frac{2}{7}+\frac{7}{7}.\frac{14}{25}\)

\(=\frac{2}{7}+1.\frac{14}{25}=\frac{2}{7}+\frac{14}{25}\)

\(=\frac{50}{175}+\frac{98}{175}=\frac{148}{175}\)

b)

\(\frac{6}{7}+\frac{5}{7}:5-\frac{8}{9}\)

\(=\frac{6}{7}+\frac{5}{30}-\frac{8}{9}\)

\(=\frac{6}{7}+\frac{1}{6}-\frac{8}{9}\)

\(=\frac{36}{42}+\frac{7}{42}-\frac{8}{9}\)

\(=\frac{43}{42}-\frac{8}{9}=\frac{129}{126}-\frac{112}{126}=\frac{17}{126}\)

tk ủng hộ mk nha!!!!!!!!

c.

\(\frac{1}{3}\times\frac{5}{7}-\frac{7}{27}\times\frac{36}{14}\)

\(=\frac{1}{3}\times\frac{5}{7}-\frac{7}{3\times9}\times\frac{4\times9}{7\times2}\)

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

\(=\frac{1}{3}\times\left(\frac{5}{7}-\frac{4}{6}\right)\)

\(=\frac{1}{3}\times\left(\frac{30-38}{42}\right)\)

\(=\frac{1}{3}\times\frac{-8}{42}\)

\(=-\frac{4}{63}\)

Chúc bạn học tốt

Sorry nha, tại mik làm biếng quá

a) \(\dfrac{2}{7}+\dfrac{7}{7}.\dfrac{14}{25}\)

\(=\dfrac{2}{7}+\dfrac{14}{25}\)

\(=\dfrac{148}{175}\)

b) \(\dfrac{6}{7}+\dfrac{5}{7}:5-\dfrac{8}{9}\)

\(=\dfrac{6}{7}+\dfrac{1}{7}-\dfrac{8}{9}\)

\(=1-\dfrac{8}{9}\)

\(=\dfrac{1}{9}\)

c) \(\left(\dfrac{-5}{28}+1,75+\dfrac{8}{35}\right):\left(-3\dfrac{9}{20}\right)\)

\(=\left(\dfrac{11}{7}+\dfrac{8}{35}\right):\left(-3\dfrac{9}{20}\right)\)

\(=\dfrac{9}{5}:\left(-3\dfrac{9}{20}\right)\)

\(=\dfrac{9}{5}:\dfrac{-69}{20}\)

\(=\dfrac{-12}{23}\)

d) \(70,5-528:\dfrac{15}{2}\)

\(=70,5-\dfrac{352}{5}\)

\(=\dfrac{1}{10}\)

e) \(\dfrac{-7}{25}.\dfrac{39}{-14}.\dfrac{50}{78}\)

\(=\dfrac{\left(-7\right).39.50}{25.\left(-14\right).78}\)

\(=\dfrac{\left(-1\right).2}{\left(-2\right).2}\)

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

a,\(\dfrac{3}{7}\).\(\dfrac{14}{5}\)=\(\dfrac{6}{5}\)

b,\(\dfrac{35}{9}\).\(\dfrac{81}{7}\)=45

c,\(\dfrac{28}{17}\).\(\dfrac{68}{14}\)=8

d,\(\dfrac{35}{46}\).\(\dfrac{23}{105}\)=\(\dfrac{1}{6}\)

e,\(\dfrac{12}{5}\):\(\dfrac{16}{15}\)=\(\dfrac{12}{5}\).\(\dfrac{15}{16}\)=\(\dfrac{9}{4}\)

i,\(\dfrac{9}{8}\):\(\dfrac{6}{5}\)=\(\dfrac{9}{8}\).\(\dfrac{5}{6}\)=\(\dfrac{15}{16}\)

a) \(49\dfrac{8}{23}-\left(5\dfrac{7}{32}+14\dfrac{8}{23}\right)\)

\(=\dfrac{1135}{23}-\left(\left(5+14\right)+\left(\dfrac{7}{32}+\dfrac{8}{23}\right)\right)\)

\(=\dfrac{1135}{23}-\left(19+\dfrac{417}{736}\right)\)

\(=\dfrac{1135}{23}-19\dfrac{417}{736}\)

\(=\dfrac{1135}{23}-\dfrac{14401}{736}\)

\(=\dfrac{953}{32}\)

b) \(-\dfrac{3}{7}\cdot\dfrac{5}{9}+\dfrac{4}{9}\cdot\dfrac{-3}{7}+2\dfrac{3}{7}\)

\(=-\dfrac{1}{7}\cdot\dfrac{5}{3}-\dfrac{4}{3}\cdot\dfrac{1}{7}+\dfrac{17}{7}\)

\(=-\dfrac{5}{21}-\dfrac{4}{21}+\dfrac{17}{7}\)

\(=2\)

c) \(0,7\cdot2\dfrac{2}{3}\cdot20\cdot0,375\cdot\dfrac{5}{28}\)

\(=\dfrac{7}{10}\cdot\dfrac{8}{3}\cdot20\cdot\dfrac{3}{8}\cdot\dfrac{5}{28}\)

\(=2\cdot\dfrac{5}{4}\)

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

d) \(\left(9\dfrac{30303}{80808}+7\dfrac{303030}{484848}\right)+4,03\)

\(=\left(9\cdot\dfrac{3}{8}+\dfrac{303030}{69264}\right)+\dfrac{403}{100}\)

\(=\left(\dfrac{27}{8}+\dfrac{35}{8}\right)+\dfrac{403}{100}\)

\(=\dfrac{31}{4}+\dfrac{403}{100}\)

\(=\dfrac{589}{50}\)

P/s: Đánh dấu phẩy, dấu chấm (dấu nhân) cần rõ ràng (vì dấu chấm người ta sẽ hiểu là dấu nhân thay vì hiểu là dấu phẩy)

a) \(49\dfrac{8}{23}\)- \(\left(5\dfrac{7}{32}+14\dfrac{8}{23}\right)\)

= \(\left(49\dfrac{8}{23}-14\dfrac{8}{23}\right)+5\dfrac{7}{32}\)

=35+\(5\dfrac{7}{32}\)

=\(\dfrac{1287}{32}\)

b)\(-\dfrac{3}{7}.\dfrac{5}{9}+\dfrac{4}{9}.\dfrac{-3}{7}+2\dfrac{3}{7}\)

=\(\left[\left(\dfrac{-3}{7}\right).\left(\dfrac{5}{9}+\dfrac{4}{9}\right)\right]+2\dfrac{3}{7}\)

=\(\left[\left(\dfrac{-3}{7}\right).\dfrac{9}{9}\right]+2\dfrac{3}{7}\)

=\(\left[\left(\dfrac{-3}{7}\right).1\right]+2\dfrac{3}{7}\)

=\(\left(\dfrac{-3}{7}\right)+2\dfrac{3}{7}\)

=2

c) 0,7.\(2\dfrac{2}{3}\).20.0.375.\(\dfrac{5}{28}\)

=0 (Vì có một thừ số là 0 nên nguyên cả tích là 0)

d)\(\left(9\dfrac{30303}{80808}+7\dfrac{303030}{484848}\right)+4,03\)

=17+4,03

=21,03

\(a,\)\(\frac{1}{2}.\left(\frac{2}{9}+\frac{3}{7}-\frac{5}{37}\right)\)

\(\Rightarrow\frac{1}{2}.\left(\frac{2.259}{2331}+\frac{3.333}{2331}-\frac{5.63}{2331}\right)\)

\(\Rightarrow\frac{1}{2}.\left(\frac{518}{2331}+\frac{999}{2331}-\frac{315}{2331}\right)\)

\(\Rightarrow\frac{1}{2}.\left(\frac{518+999-315}{2331}\right)\)

\(\Rightarrow\frac{1}{2}.\frac{1202}{2331}\)

\(\Rightarrow\frac{601}{2331}\)

\(b,\)\(\left(-\frac{5}{28}+1,75+\frac{8}{35}\right):\left(-3\frac{9}{20}\right)\)

\(\Rightarrow\frac{9}{5}:\left(-\frac{69}{20}\right)\)

\(=-\frac{12}{23}\)

\(c,\)\(\frac{1}{3}.\frac{1}{5}-\frac{7}{27}.\frac{36}{14}\)

   \(=\frac{1}{15}-\frac{2}{3}\)

\(=\frac{1}{15}-\frac{10}{15}=-\frac{9}{15}=-\frac{3}{5}\)

\(d,\)\(70,5-528:\frac{15}{2}\)

\(=70,5-\frac{352}{5}\)

\(=\frac{1}{10}\)

a) \(\dfrac{1}{2}.\left(\dfrac{2}{9}+\dfrac{3}{7}-\dfrac{5}{27}\right)\)

\(=\dfrac{1}{2}.\left(\dfrac{41}{63}-\dfrac{5}{27}\right)\)

\(=\dfrac{1}{2}.\dfrac{88}{189}\)

\(=\dfrac{44}{189}\)

b) \(\left(\dfrac{-5}{28}+1,75+\dfrac{8}{35}\right):\left(-3\dfrac{9}{20}\right)\)

\(=\left(\dfrac{11}{7}+\dfrac{8}{35}\right):\left(-3\dfrac{9}{20}\right)\)

\(=\dfrac{9}{5}:\left(-3\dfrac{9}{20}\right)\)

\(=\dfrac{9}{5}:\dfrac{-69}{20}\)

\(=\dfrac{-12}{23}\)

c) \(\dfrac{1}{3}.\dfrac{5}{7}-\dfrac{7}{27}.\dfrac{36}{14}\)

\(=\dfrac{5}{21}-\dfrac{7}{27}.\dfrac{36}{14}\)

\(=\dfrac{5}{21}-\dfrac{2}{3}\)

\(=\dfrac{-3}{7}\)

d) \(70,5-528:\dfrac{15}{2}\)

\(=70,5-\dfrac{352}{5}\)

\(=\dfrac{1}{10}\)

em không trả lời được câu hỏi của chị nhưng chị có thể giúp em đăng bài toán lên bằng cách nào không

mình ghi nhầm nên các bạn cứ hết hai phân số là một câu nhé ví dụ như \(\dfrac{-5}{8}\):\(\dfrac{15}{4}\)

B)

e) \(E=0,7.2\frac{2}{3}.20.0,375.\frac{5}{28}\)

        \(=\left(0,7.20\right)\left(2\frac{2}{3}.0,375\right)\frac{5}{28}\)

        \(=14.1.\frac{5}{28}\)

        \(=14.\frac{5}{28}\)

        \(=\frac{5}{2}\)

f) \(F=\left(9,75.21\frac{3}{7}+\frac{39}{4}.18\frac{4}{7}\right)\frac{15}{78}\)

       \(=\left(\frac{39}{4}.21\frac{3}{7}+\frac{39}{4}.18\frac{4}{7}\right)\frac{15}{78}\)

       \(=\frac{39}{4}\left(21\frac{3}{7}+18\frac{4}{7}\right)\frac{15}{78}\)

       \(=\frac{39}{4}.40.\frac{15}{78}\)

       \(=390.\frac{15}{78}\)

       \(=78\)

Chúc bạn học tốt môn Toán!!!

Mình ko ghi đề đâu

\(A=49\frac{8}{23}-5\frac{7}{32}-14\frac{8}{23}=\left(49\frac{8}{23}-14\frac{8}{23}\right)-5\frac{7}{32}=35-5\frac{7}{32}=29\frac{25}{32}\)

\(B=71\frac{38}{45}-43\frac{8}{45}+1\frac{17}{57}=\left(71\frac{38}{45}-43\frac{8}{45}\right)+1\frac{17}{57}=28\frac{2}{3}+1\frac{17}{57}=29\frac{55}{57}\)

\(C=-\frac{3}{7}.\left(\frac{5}{9}+\frac{4}{9}\right)+2\frac{3}{7}=-\frac{3}{7}.1+2\frac{3}{7}=-\frac{3}{7}+2\frac{3}{7}=2\)