a)  A= (8−$\frac{2}{3}+\frac{1}{2})$−(5−$\frac{7}{3}−\frac{3}{2})−(\frac{5}{3}+\frac{5}{2}$+4).

A=$(\frac{48}{6}−\frac{4}{6}+\frac{3}{6})−(\frac{30}{6}−\frac{14}{6}−\frac{9}{6})−(\frac{10}{6}+\frac{15}{6}+\frac{24}{6}) $

A=$\frac{47}{6}−\frac{7}{6}−\frac{49}{6}=\frac{−3}{2}$

b)  A= (8−$\frac{2}{3}+\frac{1}{2})$−(5−$\frac{7}{3}−\frac{3}{2})−(\frac{5}{3}+\frac{5}{2}$+4).

A=8−$\frac{2}{3}+\frac{1}{2}−5\frac{7}{3}+\frac{3}{2}−\frac{5}{3}−\frac{5}{2}$−4 

A=(8−5−4)+($\frac{−2}{3}+\frac{7}{3}−\frac{5}{3})+(\frac{1}{2}+\frac{3}{2}−\frac{5}{2}$)

A=−1+0−$\frac{1}{2}=\frac{−3}{2}$