a.\(\left(\frac{1}{3}-\frac{1}{4}\right)+\left(\frac{1}{4}-\frac{1}{5}\right)+\left(\frac{1}{5}-\frac{1}{6}\right)+\left(\frac{1}{6}-\frac{1}{7}\right)+\left(\frac{1}{7}-\frac{1}{8}\right)=\)
\(\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}+\frac{1}{7}-\frac{1}{8}=\frac{1}{3}-\frac{1}{8}=\frac{5}{24}\)
b. \(\frac{10}{17}-\frac{5}{13}-\frac{7}{17}-\frac{8}{13}=\left(\frac{10}{17}-\frac{7}{17}\right)-\left(\frac{5}{13}+\frac{8}{13}\right)=1-1=0\)