\(\left(2\dfrac{1}{4}-1\dfrac{1}{8}\right):\dfrac{5}{16}=\left(\dfrac{9}{4}-\dfrac{9}{8}\right).\dfrac{16}{5}=\dfrac{9}{8}.\dfrac{16}{5}=\dfrac{18}{5}\)
\(c,\dfrac{71}{1237}.\dfrac{1}{5}+\dfrac{71}{1237}.\dfrac{7}{10}+\dfrac{71}{1237}.\dfrac{1}{10}=\dfrac{71}{1237}.\left(\dfrac{1}{5}+\dfrac{7}{10}+\dfrac{1}{10}\right)=\dfrac{71}{1237}.1=\dfrac{71}{1237}\)