a; \(\dfrac{2}{5}\) x \(\dfrac{3}{4}\) + \(\dfrac{6}{15}\) : \(\dfrac{4}{9}\) x 5
= \(\dfrac{3}{10}\) + \(\dfrac{2}{5}\) x \(\dfrac{9}{4}\) x 5
= \(\dfrac{3}{10}\) + \(\dfrac{9}{10}\) x 5
= \(\dfrac{3}{10}\) + \(\dfrac{45}{10}\)
= \(\dfrac{48}{10}\)
= \(\dfrac{24}{5}\)
b; \(\dfrac{25}{12}\) x \(\dfrac{18}{35}\) x \(\dfrac{63}{24}\)
= \(\dfrac{15}{14}\) x \(\dfrac{63}{24}\)
= \(\dfrac{45}{16}\)
c; 4\(\dfrac{1}{2}\) + \(\dfrac{1}{2}\) : 5\(\dfrac{1}{2}\)
= \(\dfrac{9}{2}\) + \(\dfrac{1}{2}\) : \(\dfrac{11}{2}\)
= \(\dfrac{9}{2}\) + \(\dfrac{1}{11}\)
= \(\dfrac{99}{22}\) + \(\dfrac{2}{22}\)
= \(\dfrac{101}{22}\)