1. Вычислите: \( \frac{15}{28} - \frac{1}{20} \cdot \frac{7}{15} \).

\[ \frac{15}{28} - \frac{7}{300} = \frac{375}{700} - \frac{7}{300} = \frac{750}{1400} - \frac{98}{1400} = \frac{652}{1400} = \frac{163}{350} \] Ответ: \( \frac{163}{350} \).