б) $$\frac{13}{15} - (\frac{8}{15} + \frac{4}{15}) = \frac{13}{15} - \frac{12}{15} = \frac{1}{15}$$
в) $$( \frac{17}{100} + \frac{27}{100}) - (\frac{8}{100} + \frac{3}{100}) = \frac{44}{100} - \frac{11}{100} = \frac{33}{100}$$