\[\boxed{\mathbf{19}\mathbf{.}}\]
\[\textbf{б)}\ 40\ :5 + 62 = 8 + 62 = 70\]
\[81 + 45\ :5 = 81 + 9 = 90\]
\[70 - 5 \cdot 7 = 70 - 35 = 35\]
\[41 - 4 \cdot 8 = 41 - 32 = 9\]
\[3 \cdot 9 - 27 = 27 - 27 = 0\]
\[100 - 4 \cdot 8 = 100 - 32 = 68\]