\(B=\dfrac{13}{15}\cdot0,15\cdot3+\left(\dfrac{8}{15}-1\dfrac{19}{60}\right):\left(1\dfrac{23}{24}\right)\)

\(=\dfrac{13}{15}\cdot\dfrac{15}{100}\cdot3+\left(\dfrac{32}{60}-1-\dfrac{19}{60}\right):\dfrac{47}{24}\)

\(=\dfrac{39}{100}+\dfrac{-47}{60}\cdot\dfrac{24}{47}\)

\(=\dfrac{39}{100}-\dfrac{24}{60}=\dfrac{39}{100}-\dfrac{40}{100}=-\dfrac{1}{100}\)

\(=\dfrac{28}{15}\cdot\dfrac{1}{4}\cdot3+\dfrac{3}{8}:\left(\dfrac{32}{60}-\dfrac{69}{60}\right)\)

\(=\dfrac{7}{5}+\dfrac{3}{8}\cdot\dfrac{-60}{37}\)

\(=\dfrac{293}{370}\)

\(1\dfrac{13}{15}\cdot\left(0,5\right)^2+3\cdot\left(\dfrac{8}{15}+1\dfrac{19}{60}\right):1\dfrac{23}{24}\)

\(=\dfrac{28}{15}\cdot\dfrac{1}{4}+3\cdot\left(\dfrac{8}{15}+\dfrac{79}{60}\right):\dfrac{47}{24}\)

\(=\dfrac{7}{15}+3\cdot\dfrac{37}{20}\cdot\dfrac{24}{47}\)

\(=\dfrac{7}{15}+\dfrac{666}{235}=\dfrac{2327}{705}\)

\(1\dfrac{13}{15}.\left(0,5\right)^2+3.\left(\dfrac{8}{15}+1\dfrac{19}{60}\right):1\dfrac{23}{24}\) 

\(=\dfrac{28}{15}.\dfrac{1}{4}+3.\left(\dfrac{8}{15}+\dfrac{79}{60}\right):\dfrac{47}{24}\) 

\(=\dfrac{7}{15}+3.\dfrac{37}{20}:\dfrac{47}{24}\) 

\(=\dfrac{7}{15}+\dfrac{666}{235}\) 

\(=\dfrac{2327}{705}\)

a) \(\dfrac{-5}{9}-\dfrac{-5}{12}=\dfrac{-5}{9}+\dfrac{5}{12}=\dfrac{-20}{36}+\dfrac{15}{36}=-\dfrac{5}{36}\)

b) \(\dfrac{-5}{12}:\dfrac{15}{4}=\dfrac{-5}{12}\times\dfrac{4}{15}=\dfrac{-1}{9}\)

c) \(\dfrac{1}{13}\cdot\dfrac{8}{13}+\dfrac{5}{13}\cdot\dfrac{1}{13}-\dfrac{14}{13}=\dfrac{1}{13}\cdot\left(\dfrac{8}{13}+\dfrac{5}{13}\right)-\dfrac{14}{13}=\dfrac{1}{13}\cdot1-\dfrac{14}{13}=\dfrac{1}{13}-\dfrac{14}{13}=-1\)

a)=--5/36

b)=-1/9

c) =-1 

cách làm như trên

\(a,\dfrac{-8}{15}+\dfrac{13}{30}-\dfrac{5}{12}=\dfrac{-32}{60}+\dfrac{26}{60}-\dfrac{25}{60}=-\dfrac{31}{60}\\ b,\dfrac{3}{2}.\dfrac{7}{2}+\left(\dfrac{-5}{6}+\dfrac{1}{10}:\dfrac{11}{30}\right)=\dfrac{21}{4}+\left(\dfrac{-5}{6}+\dfrac{3}{11}\right)=\dfrac{21}{4}+\dfrac{-37}{66}=\dfrac{619}{132}\)

\(c,\dfrac{-20}{21}.\dfrac{22}{35}+\dfrac{-20}{21}.\dfrac{13}{35}+\dfrac{-22}{21}=\dfrac{-20}{21}\left(\dfrac{22}{35}+\dfrac{13}{35}\right)+\dfrac{-22}{21}=\dfrac{-20}{21}.1+\dfrac{-22}{21}=\dfrac{-20}{21}+\dfrac{-22}{21}=\dfrac{-42}{21}=-2\)

thôi thôi thôi, me khôn làm đâu

hỏi từng câu thôi:V

ít thôi

Ta có: \(M=\dfrac{9}{40}-\dfrac{11}{60}+\dfrac{13}{84}-\dfrac{15}{112}\)

\(=\dfrac{378}{1680}-\dfrac{308}{1680}+\dfrac{260}{1680}-\dfrac{225}{1680}\)

\(=\dfrac{105}{1680}=\dfrac{1}{16}\)

`16/803+38+(-16/803)`
`=16/803-16/803+38`
`=0+38=38`

`100/91+310-9/91`
`=100/91-9/91+310`
`=1+310=311`

\(\dfrac{16}{103}+\left(38+\dfrac{-16}{103}\right)\)

\(=\dfrac{16}{103}+38+\dfrac{-16}{103}\)

\(=\dfrac{16}{103}+\dfrac{-16}{103}+38\)

\(=0+38\)

\(=38\)

\(M=\dfrac{9}{40}-\dfrac{11}{60}+\dfrac{13}{84}-\dfrac{15}{112}\)

\(M=\left(\dfrac{90}{40}-\dfrac{11}{60}\right)+\left(\dfrac{13}{84}-\dfrac{15}{112}\right)\)

\(M=\dfrac{27}{120}-\dfrac{22}{120}+\dfrac{52}{336}-\dfrac{45}{336}\)

\(M=\dfrac{5}{120}+\dfrac{7}{336}\)

\(M=\dfrac{1}{24}+\dfrac{1}{48}\)

\(M=\dfrac{3}{48}=\dfrac{1}{16}\)

M=\(\dfrac{9}{40}-\dfrac{11}{60}+\dfrac{13}{84}-\dfrac{15}{112}\)

M=\(\dfrac{1}{24}+\dfrac{13}{84}-\dfrac{15}{112}\)

M=\(\dfrac{11}{56}-\dfrac{15}{112}\)

M=\(\dfrac{1}{16}\)