\(a)A=\dfrac{1}{3}-\dfrac{8}{13}-\dfrac{1}{7}+\dfrac{2}{3}+\dfrac{-7}{15}+\dfrac{8}{7}\)

     A=\((\dfrac{1}{3}+\dfrac{2}{3})-(\dfrac{8}{15}+\dfrac{-7}{15})-(\dfrac{1}{7}+\dfrac{8}{7})\)

    A=\(1-1-\dfrac{9}{7}\)

    A= 0-\(\dfrac{9}{7}\)

    A=\(-\dfrac{9}{7}\)

b) B=\(\dfrac{1}{4}+\dfrac{3}{5}-\dfrac{1}{8}-\dfrac{2}{5}+\dfrac{5}{4}\)

     B=\((\dfrac{1}{4}-\dfrac{5}{4})+(\dfrac{3}{5}+\dfrac{2}{5})-\dfrac{1}{8}\)

     B=\(-1+1-\dfrac{1}{8}\)

     B=\(0-\dfrac{1}{8}\)

     B=\(\dfrac{-1}{8}\)

a) \(\dfrac{2}{3}\times\dfrac{5}{4}-\dfrac{3}{4}\times\dfrac{2}{3}\)

    \(\dfrac{2}{3}\times(\dfrac{5}{4}-\dfrac{3}{4})\)

    \(\dfrac{2}{3}\times\dfrac{1}{2}\)

    \(\dfrac{4}{12}=\dfrac{2}{6}=\dfrac{1}{3}\)

b)\(2\times(\dfrac{-3}{2})^2-\dfrac{7}{2}\)

   \(2\times\dfrac{9}{4}-\dfrac{7}{2}\)

   \(\dfrac{9}{2}-\dfrac{7}{2}\)

   \(\dfrac{2}{2}=1\)

c)\(-\dfrac{3}{4}\times5\dfrac{3}{13}-0,75\times\dfrac{36}{13}\)

   \(-\dfrac{3}{4}\times\dfrac{68}{13}-\dfrac{3}{4}\times\dfrac{36}{13}\)

   \(-\dfrac{3}{4}\times(\dfrac{68}{13}-\dfrac{36}{13})\)

   \(-\dfrac{3}{4}\times\dfrac{32}{13}\)

   \(-\dfrac{24}{13}\)