\[\boxed{\mathbf{194.}}\]
\[\textbf{а)}\ 370 - 200 = 170\]
\[561 + 300 = 861\]
\[724 - 20 = 704\]
\[418 - 300 = 118\]
\[500 + 235 = 735\]
\[844 - 4 = 840\]
\[2)\ 934 - 10 \cdot 10 = 934 - 100 =\]
\[= 834\]
\[8 \cdot 9 + 400 = 72 + 400 = 472\]
\[745 - (318 - 18) =\]
\[= 745 - 300 = 445\]