\[\boxed{\mathbf{204.}}\]
\[1)\ 152 + 20 = 172\]
\[152 - 20 = 132\]
\[2)\ 234 + 20 = 254\]
\[234 - 20 = 214\]
\[461 + 30 = 491\]
\[461 - 30 = 431\]
\[352 + 40 = 392\]
\[352 - 40 = 312\]