Tính: phép tính

a) \(\frac{7}{8} \times \frac{2}{5}\)

= \(\frac{7}{{20}}\)

b) \(\frac{6}{{15}}:\frac{{12}}{3}\)

= \(\frac{6}{{15}} \times \frac{3}{{12}}\) = \(\frac{1}{{10}}\)

c) \(\frac{7}{4} - \frac{1}{4}:\frac{1}{2}\)

= \(\frac{7}{4} - \frac{1}{4} \times 2\) = \(\frac{7}{4} - \frac{1}{2}\) = \(\frac{5}{4}\)