\[\boxed{\mathbf{1.}}\]
\[64\ :(2 \cdot 8) = 32\ :8 = 4\]
\[81\ :(3 \cdot 9) = 9\ :3 = 3\]
\[70\ :(5 \cdot 7) = 70\ :35 = 2\]
\[96\ :(4 \cdot 3) = 96\ :12 = 8\]
\[720\ :(10 \cdot 9) = 72\ :9 = 8\]
\[540\ :(3 \cdot 10) = 54\ :3 = 18\]
\[800\ :(4 \cdot 100) = 8\ :4 = 2\]
\[600\ :(5 \cdot 10) = 60\ :5 = 12\]
\[\boxed{\mathbf{2.}}\]
\[1)\ (450 - 102)\ :4 = 348\ :4 =\]
\[= 87\]
\[2)\ 910\ :7 + 10 \cdot 19 =\]
\[= 130 + 190 = 320\]
\[3)\ (512 + 88) - 300\ :2 =\]
\[= 600 - 150 = 450\]
\[4)\ 29 \cdot 30 + 84\ :12 = 870 + 7 =\]
\[= 877\]
\[\boxed{\mathbf{3.}}\]
\[36\ :12 = 3\ (ч) - велосипедист\ \]
\[проедет\ это\ расстояние.\]
\[Правильный\ ответ:за\ 3\ часа.\]