3. 直接写出得数。
$0.75 × \dfrac{4}{5} =$
$\dfrac{4}{9} + \dfrac{7}{8} =$
$\dfrac{8}{5} ÷ \dfrac{8}{5} =$
$\dfrac{11}{12} - \dfrac{3}{4} =$
$\dfrac{7}{8} × \dfrac{2}{21} =$
$0 ÷ \dfrac{3}{11} =$
$8 - 5\dfrac{5}{7} =$
$0.9 + \dfrac{4}{9} =$

$0.75 × \dfrac{4}{5} = \dfrac{3}{5}$（或0.6）
$\dfrac{4}{9} + \dfrac{7}{8} = \dfrac{95}{72}$
$\dfrac{8}{5} ÷ \dfrac{8}{5} = 1$
$\dfrac{11}{12} - \dfrac{3}{4} = \dfrac{1}{6}$
$\dfrac{7}{8} × \dfrac{2}{21} = \dfrac{1}{12}$
$0 ÷ \dfrac{3}{11} = 0$
$8 - 5\dfrac{5}{7} = 2\dfrac{2}{7}$
$0.9 + \dfrac{4}{9} = \dfrac{121}{90}$