Tính a) \(\frac{{ - 16}}{5}.\frac{5}{{ - 4}}\)b) \(\left( {1 + \frac{1}{5}} \right).

* Hướng dẫn giải

a) \(\frac{{ - 16}}{5}.\frac{5}{{ - 4}} = \frac{4}{1}.\frac{1}{1} = 4\)

b) \(\left( {1 + \frac{1}{5}} \right).\left( {\frac{{ - 3}}{{10}} + \frac{1}{5}} \right) = \frac{6}{5}.\left( {\frac{{ - 3}}{{10}} + \frac{2}{{10}}} \right) = \frac{6}{5}.\frac{{ - 1}}{{10}} = \frac{{ - 3}}{{25}}\)