\[\boxed{\mathbf{9.}}\]
\[26 - 12 = 26 - 10 - 2 =\]
\[= 16 - 2 = 14\]
\[35 - 11 = 35 - 10 - 1 =\]
\[= 25 - 1 = 24\]
\[47 - 15 = 47 - 10 - 5 =\]
\[= 37 - 5 = 32\]
\[58 - 16 = 58 - 10 - 6 =\]
\[= 48 - 6 = 42\]
\[33 - 21 = 33 - 20 - 1 =\]
\[= 13 - 1 = 12\]
\[46 - 24 = 46 - 20 - 4 =\]
\[= 26 - 4 = 22\]
\[57 - 25 = 57 - 20 - 5 =\]
\[= 37 - 5 = 32\]
\[65 - 23 = 65 - 20 - 3 =\]
\[= 45 - 3 = 42\]
\[54 - 33 = 54 - 30 - 3 =\]
\[= 24 - 3 = 21\]
\[73 - 32 = 73 - 30 - 2 =\]
\[= 43 - 2 = 41\]
\[86 - 35 = 86 - 30 - 5 =\]
\[= 56 - 5 = 51\]
\[97 - 41 = 97 - 40 - 1 =\]
\[= 57 - 1 = 56\]