\[\boxed{\mathbf{802\ (802).}\mathbf{\ }Еуроки\ - \ ДЗ\ без\ мороки}\]
\[\frac{3}{4}\ \in B \Longrightarrow т.к.\ \ \frac{3}{4} = 0,75.\]
\[\frac{1}{15} \notin \text{B.}\]
\[\frac{7}{20}\ \in B > \Longrightarrow т.к.\ \ \frac{7}{20} = 0,35.\]
\[\frac{3}{75}\ \in B \Longrightarrow \ \ т.к.\ \ \frac{3}{75} = \frac{1}{25} = 0,04.\]
\[\frac{10}{30}\ \notin B.\]