\[\boxed{\mathbf{10}\mathbf{.}}\]
\[\textbf{а)}\ 9 + 5 = 14\]
\[8 + 4 = 12\]
\[7 + 6 = 13\]
\[11 - 3 = 8\]
\[12 - 5 = 7\]
\[13 - 4 = 9\]
\[\textbf{б)}\ 6 + 6 + 10 = 12 + 10 = 22\]
\[8 + 8 - 1 = 16 - 1 = 15\]
\[4 + 9 - 10 = 13 - 10 = 3\]
\[20 + (11 - 9) = 20 + 2 = 22\]
\[30 + (14 - 5) = 30 + 9 = 39\]
\[(40 + 10) - 1 = 50 - 1 = 49\]