\[\left( \frac{4}{5} + \frac{13}{25} \right) - \frac{8}{25} = \frac{4}{5} + \frac{13}{25} - \frac{8}{25} =\]
\[= \frac{4}{5} + \frac{5}{25} = \frac{4}{5} + \frac{1}{5} = \frac{5}{5} = 1.\]