lỗi xíu thôi, sorry nha

\(\dfrac{1}{3}+\dfrac{5}{4}=\dfrac{4}{12}+\dfrac{15}{12}=\dfrac{19}{12}\)

_____________________________\(\dfrac{4}{12}-\dfrac{1}{15}=\dfrac{60}{180}-\dfrac{12}{180}=\dfrac{48}{180}=\dfrac{4}{15}\)

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\(\dfrac{2}{3}\)x\(\dfrac{15}{8}\)\(=\dfrac{30}{24}=\dfrac{5}{4}\)

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\(\dfrac{2}{3}:\dfrac{8}{21}=\dfrac{2}{3}\)x\(\dfrac{21}{8}=\)\(\dfrac{42}{24}=\dfrac{7}{4}\)

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D. 28 000 000 \(m^2\)

D.\(\dfrac{1}{2}\)

C.35

C. \(\dfrac{1}{4}\)

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\(8-\dfrac{1}{15}\)x\(\dfrac{15}{3}\)

\(=8-\)\(\dfrac{15}{45}\)

\(=8-\dfrac{1}{3}\)

\(=\dfrac{24}{3}-\dfrac{1}{3}\)

\(=\dfrac{23}{3}\)

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\(\dfrac{8}{10}+\dfrac{4}{5}\)

\(=\dfrac{8}{10}+\dfrac{8}{10}\)

\(=\dfrac{16}{10}=\dfrac{8}{5}\)

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\(\dfrac{1}{2}-\dfrac{3}{8}\)

\(=\dfrac{4}{8}-\dfrac{3}{8}\)

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

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