Tính nhanh
\(A = \frac{1}{3} - \frac{3}{4} - \left( {\frac{{ - 3}}{5}} \right) + \frac{1}{{72}} - \frac{2}{9} - \frac{1}{{36}} + \frac{1}{{15}}\)
\(\begin{array}{l}
A = \left( {\frac{1}{3} + \frac{3}{5} + \frac{1}{{15}}} \right) - \left( {\frac{3}{4} + \frac{2}{9} + \frac{1}{{36}}} \right) + \frac{1}{{72}}\\
= 1 - 1 + \frac{1}{{72}} = \frac{1}{{72}}
\end{array}\)
-- Mod Toán 7
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