[tex]A=\frac{-1}{2}+\frac{3}{5}+\frac{-1}{9}+\frac{1}{131}+\frac{2}{7}+\frac{4}{35}-\frac{7}{18}\\A=\left ( \frac{-1}{2}+\frac{-1}{9}-\frac{7}{18} \right) +\left ( \frac{3}{5}+\frac{2}{7}+\frac{4}{35} \right )+\frac{1}{131}\\A=-1+1+\frac{1}{131}=\frac{1}{131}[/tex]