a) −0,375+$\frac{1}{4}−(−\frac{1}{5})=\frac{3}{40}$

b) $\frac{2}{3}+(\frac{−5}{12})+(\frac{−7}{15})$+(−0,2)=$−\frac{5}{12}$

c) 0,275+$(\frac{−8}{17})+\frac{29}{40}+(\frac{−9}{17})−1\frac{1}{3}=\frac{11}{40}+\frac{29}{40}+(\frac{−8}{17})+(\frac{−9}{17})−1\frac{1}{3}=−1\frac{1}{3}$

d) (−5).$(\frac{−34}{21}).(\frac{−7}{10}).(−\frac{3}{17})$=(−0,5).$(\frac{−34}{21}).(−\frac{3}{17}).(\frac{−7}{10})$=(−5).$\frac{2}{7}.(\frac{−7}{10})$=1

e) $(\frac{13}{18}:\frac{26}{9}).\frac{4}{7}=(\frac{13}{18}.\frac{9}{26}).\frac{4}{7}=\frac{1}{7}$

f) $[(\frac{−5}{33}):\frac{2}{11}]$.0,15=$[(−\frac{5}{33}).\frac{11}{2}]\frac{3}{20}=\frac{−1}{8}$