§ Задание 264
\[\boxed{\mathbf{2.2}\mathbf{64}}\]

\[P = 4a;\ \ \ a = \frac{5}{16}\ дм:\]
\[P = 4 \cdot \frac{5}{16} = \frac{4 \cdot 5}{16} = \frac{5}{4} =\]
\[= 1\frac{1}{4}\ (дм).\]
\[Ответ:1\frac{1}{4}\ дм.\]
\[\boxed{\mathbf{2.2}\mathbf{64}}\]

\[P = 4a;\ \ \ a = \frac{5}{16}\ дм:\]
\[P = 4 \cdot \frac{5}{16} = \frac{4 \cdot 5}{16} = \frac{5}{4} =\]
\[= 1\frac{1}{4}\ (дм).\]
\[Ответ:1\frac{1}{4}\ дм.\]