Tính:

----- Nội dung ảnh -----
\[
\left( \frac{1}{8} + \frac{1}{3} \right) \left( \frac{1}{5} - \frac{1}{4} \right) - \left( \frac{1}{4} + \frac{1}{5} \right) = \left( \frac{1}{90} + \frac{1}{100} \right)
\]