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

d.

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

\(=70,5-528\div7,5\)

\(=70,5-70,4\)

\(=0,1\)

Chúc bạn học tốt

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

A) \(\frac{1}{2}\cdot\left(\frac{2}{9}+\frac{3}{7}-\frac{5}{27}\right)\) 

\(=\frac{1}{2}\cdot\frac{1}{2}\)

\(=\frac{1}{4}\)

B)   \(\left(\frac{-5}{28}+1.75+\frac{8}{35}\right):\left(-3\frac{9}{20}\right)\)

\(=\left(\frac{-5}{28}+\frac{7}{4}+\frac{8}{35}\right):\frac{-69}{20}\)

\(=\frac{14}{5}:\frac{-69}{20}\)

\(=\frac{-56}{69}\)

Giải:

a) \(\left(-\dfrac{5}{28}+1,75+\dfrac{8}{35}\right):\left(\dfrac{-39}{20}\right)\)

\(=\left(-\dfrac{5}{28}+\dfrac{7}{4}+\dfrac{8}{35}\right):\left(\dfrac{-39}{20}\right)\)

\(=\left(\dfrac{11}{7}+\dfrac{8}{35}\right):\left(-\dfrac{39}{20}\right)\)

\(=\dfrac{9}{5}:\left(-\dfrac{39}{20}\right)\)

\(=\dfrac{9.\left(-20\right)}{5.39}\)

\(=\dfrac{3.\left(-4\right)}{1.13}\)

\(=\dfrac{-12}{13}\)

b) \(6\dfrac{5}{12}:2\dfrac{3}{4}+11\dfrac{1}{4}.\left(\dfrac{1}{3}+\dfrac{1}{5}\right)\)

\(=\dfrac{77}{22}:\dfrac{11}{4}+\dfrac{42}{4}.\left(\dfrac{1}{3}+\dfrac{1}{5}\right)\)

\(=\dfrac{77}{22}.\dfrac{4}{11}+\dfrac{42}{4}.\left(\dfrac{5}{15}+\dfrac{3}{15}\right)\)

\(=\dfrac{7}{3}+\dfrac{42}{4}.\dfrac{8}{15}\)

\(=\dfrac{7}{3}+\dfrac{14.2}{1.3}\)

\(=\dfrac{7}{3}+\dfrac{28}{3}\)

\(=\dfrac{35}{3}\)

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

\(=70,5-528.\dfrac{2}{15}\)

\(=70,5-\dfrac{1056}{15}\)

\(=70,5-70,4\)

\(=0,1\)

b/\(1\frac{2}{9}\)

Bài 1:

a) \(-\frac{3}{7}+\frac{15}{26}-\left(\frac{2}{13}-\frac{3}{7}\right)\)

\(=-\frac{3}{7}+\frac{15}{26}-\frac{4}{26}+\frac{3}{7}\)

\(=\left(-\frac{3}{7}+\frac{3}{7}\right)+\left(\frac{15}{26}-\frac{4}{26}\right)\)

\(=0+\frac{11}{26}\)

\(=\frac{11}{26}\)

b)\(2\frac{3}{7}+\frac{2}{9}-1\frac{3}{7}\)

\(=\frac{17}{7}+\frac{2}{9}-\frac{10}{7}\)

\(=\left(\frac{17}{7}-\frac{10}{7}\right)+\frac{2}{9}\)

\(=1+\frac{2}{9}\)

\(=1\frac{2}{9}=\frac{11}{9}\)

c)\(\left(\frac{377}{-231}-\frac{124}{89}+\frac{34}{791}\right).\left(\frac{1}{6}-\frac{1}{8}-\frac{1}{24}\right)\)

\(=\left(\frac{377}{-231}-\frac{124}{89}+\frac{34}{791}\right).\left(\frac{4}{24}-\frac{3}{24}-\frac{1}{24}\right)\)

\(=\left(\frac{377}{-231}-\frac{124}{89}+\frac{34}{791}\right).0\)

\(=0\)

\(B1:\)  \(a,\frac{-3}{7}+\frac{15}{26}-\frac{2}{13}+\frac{3}{7}\)

= \(\left(\frac{15}{26}-\frac{2}{13}\right)+\left(\frac{3}{7}+\frac{-3}{7}\right)\)

= \(\frac{11}{26}+0=\frac{11}{26}\)

\(b,2\frac{3}{7}-1\frac{3}{7}+\frac{2}{9}\)

= \(1+\frac{2}{9}=1\frac{2}{9}\)

\(c,\left(\frac{377}{-231}-\frac{124}{89}+\frac{34}{791}\right).\left(\frac{4}{24}-\frac{3}{24}-\frac{1}{24}\right)\)

= \(\left(\frac{377}{-231}-\frac{124}{89}+\frac{34}{791}\right).0=0\)

\(B2:\)\(a,\frac{1}{2}.\left(\frac{2}{9}+\frac{3}{12}-\frac{5}{27}\right)\)

= \(\frac{1}{2}.\left(\frac{17}{36}-\frac{5}{27}\right)\)

= \(\frac{1}{2}.\left(\frac{31}{108}\right)\)

= \(\frac{31}{216}\)

b, \(\left(1\frac{4}{5}\right):-3\frac{9}{20}\)

= \(\frac{-12}{23}\)

c, \(\frac{5}{21}-2\frac{11}{14}\)

= \(-2\frac{23}{42}\)

d, \(70\frac{1}{2}-70\frac{2}{5}\)

= \(1\frac{1}{704}\)

B1:

a,\(\frac{-3}{7}+\frac{15}{26}-\left(\frac{2}{13}-\frac{3}{7}\right)\)

\(\Rightarrow\frac{-3}{7}+\frac{15}{26}-\frac{2}{13}+\frac{3}{7}\)

\(\Rightarrow\left(\frac{-3}{7}+\frac{3}{7}\right)+\frac{15}{26}-\frac{4}{26}\)

\(\Rightarrow\frac{15}{26}-\frac{4}{26}\)

=\(\frac{11}{26}\)

b,\(\frac{23}{7}+\frac{2}{9}-\frac{13}{7}\)

\(=\frac{23}{7}-\frac{13}{7}+\frac{2}{9}\)

\(=\frac{10}{7}+\frac{2}{9}\)

\(=\frac{104}{63}\)

c,\(\left(\frac{377}{-231}-\frac{124}{89}+\frac{34}{791}\right).\left(\frac{1}{6}-\frac{1}{8}-\frac{1}{24}\right)\)

\(=\left(\frac{377}{-231}-\frac{124}{89}+\frac{34}{791}\right).0\)

\(=0\)

a, 1/2 x ( 2/9 + 3/7 - 5/27 )

= 1/2 x ( 41/63 - 5/27 )

= 1/2 x 88/189

= 44/189

b, (-5/8 + 1,75 + 8/35) : (-3 và 9/10)

= (-5/8 + 7/4 + 8/35) : (-39/10)

= (9/8 + 8/35) : (-39/10)

=379/280 : (-39/10)

= -379/1092

c, 1/3 x 5/7 - 5/27 x 36/14

= 5/21 - 10/21

= -5/21

Chúc bạn học tốt !

a) 1/2 x  (\(\frac{42}{189}-\frac{81}{189}-\frac{35}{189}\))=1/2 x 88/189 = 44/189

b) ( \(\frac{-5}{8}+\frac{7}{4}+\frac{8}{35}\)) : \(-3\frac{9}{10}\)

= ( \(\frac{-175}{280}+\frac{490}{280}+\frac{64}{280}\)) : \(\frac{-39}{10}\)

=\(\frac{379}{280}\)  x \(\frac{-10}{39}\)=\(\frac{-379}{1092}\)

c) \(\frac{5}{21}\)- \(\frac{10}{21}\)= \(\frac{-5}{21}\)

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!!!!!!!!

a.-1,75-(-\(\dfrac{1}{9}\)-2\(\dfrac{1}{8}\))
-1,75-\(\dfrac{1}{9}+\dfrac{17}{8}\)
\(-\dfrac{7}{4}-\dfrac{1}{9}+\dfrac{17}{8}\)
\(\dfrac{-126}{72}-\dfrac{8}{72}+\dfrac{153}{72}\)
=\(\dfrac{19}{72}\)

b.\(\dfrac{-1}{12}-\left(2\dfrac{5}{8}-\dfrac{1}{3}\right)\)
\(\dfrac{-1}{12}-\left(\dfrac{21}{8}-\dfrac{1}{3}\right)\)
\(\dfrac{-1}{12}-\dfrac{21}{8}+\dfrac{1}{3}\)
\(\dfrac{-2}{24}-\dfrac{63}{24}+\dfrac{64}{24}\)
=\(\dfrac{-1}{24}\)

\(\dfrac{-5}{6}-\left(\dfrac{-3}{8}+\dfrac{1}{10}\right)\)
\(\dfrac{-5}{6}-\dfrac{-3}{8}-\dfrac{1}{10}\)