\[\boxed{\mathbf{4.172}}\]
\[\textbf{а)}\ 574 \cdot (4086 + 3092) =\]
\[= 574 \cdot 7178 = 4\ 120\ 172\]
\[\textbf{б)}\ 678 \cdot (55\ 152 - 54\ 663) =\]
\[= 678 \cdot 489 = 331\ 542\]
\[\textbf{в)}\ 1\ 452\ 168\ :(5690 - 5474) =\]
\[= 1\ 452\ 168\ :216 = 6723\]
\[\textbf{г)}\ 1\ 686\ 073\ :(5100 - 4753) =\]
\[= 1\ 686\ 073\ :347 = 4859\]