\[Страница\ 31\]
\[\boxed{\mathbf{8.}}\]
\[1)\ 7 - 3 = 4\ (р.)\]
\[схема\ 3.\]
\[2)\ 7 - 4 = 3\ (р.)\]
\[схема\ 1.\]
\[3)\ 4 + 3 = 7\ (р.)\]
\[схема\ 2.\]
\[\boxed{\mathbf{9.}}\]
\[1)\ 9 + 8 = 9 + 1 + 7\]
\[8 + 5 = 8 + 2 + 3\]
\[7 + 6 = 7 + 3 + 3\]
\[9 + 7 = 9 + 1 + 6\]
\[2)\ 7 + 4 = 3 + 8\]
\[6 + 9 = 8 + 7\]
\[4 + 9 = 6 + 7\]
\[9 + 9 = 9 + 9\]