\[\boxed{\mathbf{23.}}\]
\[9 + 4 + 30 = 13 + 30 = 43\]
\[20 + (8 + 6) = 20 + 14 = 34\]
\[40 + (7 + 5) = 40 + 12 = 52\]
\[60 - (18 + 2) = 60 - 20 = 40\]
\[11 - 4 + 70 = 7 + 70 = 77\]
\[51 + (13 - 6) = 51 + 7 = 58\]
\[33 + (11 - 5) = 33 + 6 = 39\]
\[6 + 9 + 40 = 15 + 40 = 55\]
\[60 + (8 + 5) = 60 + 13 = 73\]