\[\boxed{\mathbf{9.}}\]
\[\textbf{а)}\ 49 + 8 = 57\]
\[65 + 7 = 72\]
\[4 + 57 = 61\]
\[33 - 6 = 27\]
\[46 - 8 = 38\]
\[77 - 9 = 68\]
\[\textbf{б)}\ 53 - 4 + 6 = 49 + 6 = 59\]
\[74 - (38 - 32) = 74 - 6 = 68\]
\[89 + (69 - 64) = 89 + 5 = 94\]