Câu trả lời:

a/ \(\dfrac{x}{7}\)=\(\dfrac{18}{14}\)

x = \(\dfrac{18.7}{14}\)

x = \(\dfrac{126}{14}\)

x = 9 \(\Rightarrow\) x = 9 b/ 6: x =\(1\dfrac{3}{4}\):5 x = \(\dfrac{6.5}{1\dfrac{3}{4}}\) x = 30 : \(\dfrac{7}{4}\) x = \(\dfrac{120}{7}\) \(\Rightarrow\) x = \(\dfrac{120}{7}\) c/ 5,7:0,35= (-x) :0,45 -x =\(\dfrac{5,7.0,45}{0,35}\) -x =\(\dfrac{2,565}{0,35}\) -x = \(\dfrac{513}{70}\) \(\Leftrightarrow\) x = \(\dfrac{-513}{70}\)

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