Đáp án:
Giải thích các bước giải:
Ta có: $\dfrac{27}{-180}$=$\dfrac{-3}{20}$ ; $\dfrac{-6}{-35}$=$\dfrac{6}{35}$
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$\dfrac{-3}{-28}$=$\dfrac{3}{28}$
MSC:$140$
$\dfrac{6}{35}$=$\dfrac{6.4}{35.4}$=$\dfrac{24}{140}$
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$\dfrac{-3}{20}$=$\dfrac{-3.7}{20.7}$=$\dfrac{-21}{140}$
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$\dfrac{3}{28}$=$\dfrac{3.5}{28.5}$=$\dfrac{15}{140}$