a)
(3\frac{3}{5}+2\frac{8}{10})*1\frac{1}{7}=(\frac{18}{5}+\frac{28}{10})*\frac{8}{7}=(\frac{18}{5}+\frac{14}{5})*\frac{8}{7}=\frac{32}{5}*\frac{8}{7}=\frac{256}{35}=7\frac{11}{35}
b)
\frac{\not3^1}{\not4^2}*\frac{\not2^1}{\not9^3}=\frac{1}{2}*\frac{1}{3}=\frac{1}{6}
c)
1\frac{2}{3}*(1\frac{1}{2}-\frac{3}{4})=\frac{5}{3}-(\frac{3}{2}-\frac{3}{4})=\frac{20}{12}-(\frac{18}{12}-\frac{9}{12})=\frac{20}{12}-\frac{9}{12}=\frac{11}{12}