Thực hiện phép tính (hợp lí nếu có thể): (a) ( − 2 , 671 ) + ( − 5 , 383 ) . (b) 5/8 − 7/12 + 6/16 .

a) \(\left( { - 2,671} \right) + \left( { - 5,383} \right)\)

\( = - 8,504\).

b) \(\frac{5}{8} - \frac{7}{{12}} + \frac{6}{{16}}\)\( = \frac{5}{8} - \frac{7}{{12}} + \frac{3}{8}\)

\( = \left( {\frac{5}{8} + \frac{3}{8}} \right) - \frac{7}{{12}}\)\( = 1 - \frac{7}{{12}} = \frac{{12}}{{12}} - \frac{7}{{12}} = \frac{5}{{12}}.\)

c) \(\frac{{35}}{{16}} + \frac{4}{7} - \frac{6}{{32}} - \frac{{18}}{7} + \frac{2}{3}\)

\( = \frac{{35}}{{16}} + \frac{4}{7} - \frac{3}{{16}} - \frac{{18}}{7} + \frac{2}{3}\)

\( = \left( {\frac{{35}}{{16}} - \frac{3}{{16}}} \right) + \left( {\frac{4}{7} - \frac{{18}}{7}} \right) + \frac{2}{3}\)

\( = \frac{{32}}{{16}} + \frac{{ - 14}}{7} + \frac{2}{3}\)

\( = 2 + \left( { - 2} \right) + \frac{2}{3} = \frac{2}{3}\).

d) \(\frac{{ - 5}}{7}.\frac{2}{{11}} + \frac{{ - 5}}{7}.\frac{9}{{11}} + 1\frac{5}{7}\)

\( = \frac{{ - 5}}{7}\left( {\frac{2}{{11}} + \frac{9}{{11}}} \right) + 1\frac{5}{7}\)

\( = \frac{{ - 5}}{7}.\frac{{11}}{{11}} + 1\frac{5}{7}\)

\( = \frac{{ - 5}}{7} + 1 + \frac{5}{7}\)

\( = \left( {\frac{{ - 5}}{7} + \frac{5}{7}} \right) + 1 = \frac{5}{7}\).