\[\boxed{\text{Вопрос}\text{\ }\text{на}\text{\ }\text{стр}\text{.\ 25}}\]
\[84\ :(2 \cdot 6) = 84\ :12 = 7\]
\[210\ :(7 \cdot 6) = 210\ :7\ :6 =\]
\[= 30\ :6 = 5\]
\[400\ :(10 \cdot 8) = 400\ :10\ :8 =\]
\[= 40\ :8 = 5\]