\(\frac{1}{3}.\frac{5}{7}-\frac{7}{27}.\frac{36}{14}\)
\(=\frac{1}{3}.\frac{5}{7}-\frac{7}{27}.\frac{18}{7}\)
\(=\frac{1.5}{3.7}-\frac{7.18}{27.7}\)
\(=\frac{5}{21}-\frac{2}{3}\)
\(=\frac{5}{21}-\frac{14}{21}=\frac{-9}{21}=\frac{-3}{7}\)
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