Thực hiện phép tính:(a) −0,32.(−0,875);(b) (-5) : 2 1/5

a) −0,32.(−0,875)

\( = - \frac{{32}}{{100}}.\left( { - \frac{{875}}{{1000}}} \right)\)

\( = \frac{8}{{25}}.\frac{7}{8} = \frac{7}{{25}}\).

b) \(\left( { - 5} \right):2\frac{1}{5}\)

\( = \left( { - 5} \right):\frac{{11}}{5} = \left( { - 5} \right).\frac{5}{{11}} = - \frac{{25}}{{11}}\).