\[Страница\ 79.\]
\[\boxed{\mathbf{13.}}\]
\[18 + 12 = 30\ (человек) -\]
\[вмещает\ одна\ лодка.\]
\[30 \cdot 3 + 18 =\]
\[= 108\ (экскурсантов) - было.\]
\[Ответ:108\ экскурсантов.\]
\[\boxed{\mathbf{14.}}\]
\[\textbf{а)}\ x\ :18 = 16\ (ост.\ 17)\]
\[x = 16 \cdot 18 + 17\]
\[x = 288 + 17\]
\[x = 305.\]
\[\textbf{б)}\ 863\ :x = 26\ (ост.\ 5)\]
\[863 = 26 \cdot x + 5\]
\[x = (863 - 5)\ :26\]
\[x = 858\ :26\]
\[x = 33.\]