\[\boxed{\mathbf{177.}}\]
\[\textbf{а)}\ 106 + 20 = 126\]
\[408 - 400 = 8\]
\[500 + 300 = 800\]
\[283 - 80 = 203\]
\[600 - 500 = 100\]
\[704 - 4 = 700\]
\[\textbf{б)}\ 895 - (37 + 58) =\]
\[= 895 - 95 = 800\]
\[300 + (93 - 27) = 300 + 66 =\]
\[= 366\]
\[981 - 9 \cdot 9 = 981 - 81 = 900\]