0.7 -12   6   3

 1   2   -1  -8

-3   4    5   0

 5  -7    0   4

Const
 A:Array[1..4,1..4] of Real=((0.7,-12, 6, 3),(1, 2,-1,-8),
                             ( -3,  4, 5, 0),(5,-7, 0, 4));
Var
 i,j,k:byte;
 Ar_Mean:Real;

Begin
 writeln('Initial matrix:');
 for i:=1 to 4 do
  begin
   for j:=1 to 4 do
    write(A[i,j]:8:2);
   writeln;
  end;
 writeln;
 k:=0;
 Ar_Mean:=0;
 for i:=1 to 3 do
  for j:=1 to 4-i do
   begin
    Ar_Mean:=Ar_Mean+A[i,j];
    k:=k+1;
   end;
 Ar_Mean:=Ar_Mean/k;
 writeln('Arithmetic mean = ',Ar_Mean:0:5);
 writeln;
 writeln('New matrix:');
 for i:=1 to 4 do
  begin
   for j:=1 to 4 do
    begin
     A[i,j]:=A[i,j]*Ar_Mean;
     write(A[i,j]:8:2);
    end;
   writeln;
  end;
 Readln
End.