Tính bằng cách thuận tiện. a) 7/8 x 14/15 + 7/8 x 16/15

a) \(\frac{7}{8} \times \frac{{14}}{{15}} + \frac{7}{8} \times \frac{{16}}{{15}}\)

= \(\frac{7}{8} \times \left( {\frac{{14}}{{15}} + \frac{{16}}{{15}}} \right)\)

= \(\frac{7}{8} \times 2\)

= \(\frac{7}{4}\)

b) \(\frac{{19}}{{10}}:\frac{1}{3} + \frac{{19}}{{10}}:\frac{1}{9} - \frac{{19}}{{10}}:\frac{1}{2}\)

= \(\frac{{19}}{{10}} \times 3 + \frac{{19}}{{10}} \times 9 - \frac{{19}}{{10}} \times 2\)

= \(\frac{{19}}{{10}} \times \left( {3 + 9 - 2} \right)\)

= \(\frac{{19}}{{10}} \times 10 = 19\)