a) (−0,5)−(−1+$\frac{2}{3})$:1,5+$(\frac{−1}{4})$=$(\frac{−1}{2)}−(\frac{−1}{3}).\frac{2}{3}+(\frac{−1}{4})=(\frac{−1}{2})+\frac{2}{9}+(\frac{−1}{4})=\frac{−19}{36}$

b) $[(\frac{−7}{8}:\frac{21}{16}]−\frac{5}{3}.(\frac{1}{3}−\frac{7}{10})= [(\frac{−7}{8}).\frac{16}{21}]−\frac{5}{3}.(\frac{−11}{10})=(\frac{−2}{3})+\frac{11}{6}=\frac{7}{6}$

c) $[(\frac{−2}{3})+\frac{3}{4}]^{2}.\frac{12}{5}−\frac{1}{5}= (\frac{1}{12})^{2}.\frac{12}{5}−\frac{1}{5}=\frac{1}{60}−\frac{1}{5}=\frac{−11}{60}$

d) $(\frac{1}{25}−0,4)^{2}:\frac{9}{125}−[(1\frac{1}{3}−\frac{2}{5}).\frac{3}{7}]= (\frac{−9}{25})^{2}:\frac{9}{125}−(\frac{14}{5}.\frac{3}{7})=\frac{9}{5}−\frac{2}{5}=\frac{7}{5}$

e) $3\frac{17}{18}.[\frac{5}{2}−(\frac{1}{3}+\frac{2}{9}]:[(\frac{−1}{2})+0,25]^{2}=\frac{71}{18}.[\frac{5}{2}−\frac{5}{9}]:(\frac{−1}{4})^{2}=\frac{2485}{324}:\frac{1}{16}=\frac{9940}{81}$