Thực hiện phép tính (tính hợp lí nếu có thể): (a) 5 /7 − 4/ 7 . 1 /6

a) \[\frac{5}{7} - \frac{4}{7}.\frac{1}{6} = \frac{5}{7} - \frac{2}{{21}} = \frac{{15}}{{21}} - \frac{2}{{21}} = \frac{{13}}{{21}}\];

b) \(\frac{{ - 5}}{{12}} + \frac{4}{{37}} + \frac{{17}}{{12}} - \frac{{41}}{{37}}\)\( = \left( {\frac{{ - 5}}{{12}} + \frac{{17}}{{12}}} \right) + \left( {\frac{4}{{37}} - \frac{{41}}{{37}}} \right)\)\( = 1 - 1\)\( = 0\);

c) \(\frac{{ - 11}}{{24}}:\frac{{17}}{{23}} - \frac{{11}}{{24}}:\frac{{17}}{{11}} - \frac{1}{{12}}\)

\( = \frac{{ - 11}}{{24}}.\frac{{23}}{{17}} - \frac{{11}}{{24}}.\frac{{11}}{{17}} - \frac{1}{{12}}\)

\( = \frac{{ - 11}}{{24}}.\left( {\frac{{23}}{{17}} + \frac{{11}}{{17}}} \right) - \frac{1}{{12}}\)

\( = \frac{{ - 11}}{{24}}.2 - \frac{1}{{12}}\)\( = \frac{{ - 11}}{{12}} - \frac{1}{{12}}\)\( = - 1\)