Tính bằng cách thuận tiện: 7/9 × 6/5 + 6/5 × 2/9 + 4/5

\(\frac{7}{9} \times \frac{6}{5} + \frac{6}{5} \times \frac{2}{9} + \frac{4}{5}\)

\( = \frac{6}{5} \times \left( {\frac{7}{9} + \frac{2}{9}} \right) + \frac{4}{5}\)

\( = \frac{6}{5} \times \frac{9}{9} + \frac{4}{5}\)

\( = \frac{6}{5} \times 1 + \frac{4}{5}\)

\( = \frac{6}{5} + \frac{4}{5} = \frac{{10}}{5} = 2\)