Thực hiện phép tính (tính hợp lí nếu có thể):  a) 60,7 + 25,5 - 38,7;b) 6/5- 1/5:3/10

a) \[60,7 + 25,5-38,7\]

\[ = 86,2-38,7\]

\( = 47,5\).

b) \(\frac{6}{5} - \frac{1}{5}:\frac{3}{{10}}\)

\( = \frac{6}{5} - \frac{1}{5}.\frac{{10}}{3}\)

\( = \frac{6}{5} - \frac{2}{3}\)

\( = \frac{{18}}{{15}} - \frac{{10}}{{15}} = \frac{8}{{15}}\).

c) \[\left( {4 - 1,2} \right):2 + 30\% \]

\[ = 2,8:2 + 0,3\]

\[ = 1,4 + 0,3\]

\[ = 1,7\].

d) \(\frac{1}{7} \cdot \frac{1}{3} + \frac{1}{7} \cdot \frac{1}{2} - \frac{1}{7}\)

\( = \frac{1}{7}.\left( {\frac{1}{3} + \frac{1}{2} - 1} \right)\)

\( = \frac{1}{7}.\left( {\frac{2}{6} + \frac{3}{6} - \frac{6}{6}} \right)\)

\( = \frac{1}{7}.\frac{{ - 1}}{6} = \frac{{ - 1}}{{42}}\).