\[\boxed{\text{П.77.}}\]
\[\textbf{а)}\ (266\ 465 - 93\ 281)\ :1\ 408 =\]
\[= 173\ 184\ :1\ 408 = 123\ \]
\[\textbf{б)}\ 157\ 464\ :(17\ 496\ :27) =\]
\[= 157\ 464\ :648 = 243\ \]
\[\textbf{в)}\ 1\ 634\ 697\ :(5\ 747 - 838) =\]
\[= 1\ 634\ 697\ :4\ 909 = 333\ \]
\[\textbf{г)}\ 509\ 927\ :(287\ 353\ :173) =\]
\[= 509\ 927\ :1\ 661 = 307\]