\[\boxed{\text{4.\ 376}}\]
\[\textbf{а)}\ 6 \cdot (x - 7) = 0\]
\[x - 7 = 0\]
\[x = 7.\]
\[\textbf{б)} - 11 \cdot (5,4 + x) = 0\]
\[5,4 + x = 0\]
\[x = - 5,4.\]
\[\textbf{в)}\ 2,9 \cdot (36 - x) = 0\]
\[36 - x = 0\]
\[x = 36.\]
\[\textbf{г)}\ (2x - 8) \cdot 4,7 = 0\]
\[2x - 8 = 0\]
\[2x = 8\]
\[x = 4.\]