\[\boxed{\text{4.\ 312}}\]
\[\textbf{а)} - 6 \cdot ( - 5) - ( - 40)\ :8 =\]
\[= 30 + 5 = 35\]
\[\textbf{б)}\ 27\ :( - 27) - ( - 35)\ :7 =\]
\[= - 1 + 5 = 4\]
\[\textbf{в)} - 7 \cdot ( - 7 + 15)\ :28 + 3 =\]
\[= - 7 \cdot 8\ :28 + 3 = - 2 + 3 = 1\]
\[\textbf{г)}\ 7,4 \cdot ( - 7 - 3)\ :5 = - 74\ :5 =\]
\[= - 14,8\]
\[\textbf{д)}\ ( - 9 + 31)\ :( - 11) - 5 =\]
\[= - 2 - 5 = - 7\]
\[\textbf{е)} - 40 + ( - 4 - 5 + 6)\ :( - 3) =\]
\[= - 40 + 1 = - 39\]
\[\textbf{ж)} - 5 \cdot 8 - 48\ :( - 4,3 + 2,7) =\]
\[= - 40 - 48\ :( - 1,6) =\]
\[= - 40 + 30 = - 10\]
\[= ( - 8,4)\ :( - 7) \cdot ( - 5) =\]
\[= 1,2 \cdot ( - 5) = - 6\]