§ Задание 21
\[\boxed{\mathbf{1}\mathbf{.21}}\]
\[\textbf{а)}\ 15\ и\ 21 - 5\ чисел:\]
\[21 - 15 - 1 = 5.\]
\[\textbf{б)}\ 34\ и\ 43 - 8\ чисел:\]
\[43 - 34 - 1 = 8.\]
\[\boxed{\mathbf{1}\mathbf{.21}}\]
\[\textbf{а)}\ 15\ и\ 21 - 5\ чисел:\]
\[21 - 15 - 1 = 5.\]
\[\textbf{б)}\ 34\ и\ 43 - 8\ чисел:\]
\[43 - 34 - 1 = 8.\]