\[\boxed{\mathbf{12.}}\]
\[\textbf{а)}\ 22 + 8 = 30\]
\[44 + 6 = 50\]
\[77 + 3 = 80\]
\[65 + 5 = 70\]
\[94 + 6 = 100\]
\[92 + 8 = 100\]
\[\textbf{б)}\ 48 - 12 + 4 = 36 + 4 = 40\]
\[53 + 7 - 1 = 60 - 1 = 59\]
\[61 - 30 + 9 = 31 + 9 = 40\]
\[36 + (11 - 7) = 36 + 4 = 40\]
\[85 - 21 + 6 = 64 + 6 = 70\]
\[97 + (12 - 9) = 97 + 3 = 100\]