const n=5;
type ar=array[1..n,1..n] of integer;
procedure p1(var m:ar);
var i,j:integer;
begin
for i:=1 to n do
  for j:=1 to n do m[i,j]:=random(10)-5;
end;

procedure p2(h:string[2];var m:ar);
var i,j:integer;
begin
writeln('--',h,'--');
for i:=1 to n do
 begin
  for j:=1 to n do write(m[i,j]:4);
  writeln;
 end; 
end;
 
procedure p3(var m1,m2,m3:ar);
var i,j,k,s:integer;
begin
for i:=1 to n do 
 for j:=1 to n do
 begin
 s:=0;
 For k := 1 to n do s:=s+m1[i,k]*m2[k,j];
 m3[i,j]:=s;
 end;
end;

procedure p4(var m1,m2,m3:ar);
var i,j:integer;
begin
for i:=1 to n do 
 for j:=1 to n do m3[i,j]:=m1[i,j]-m2[i,j];
end;

var a,b,ab,ba,c : ar; 
begin
Randomize;
p1(a); p2('A',a);
p1(b); p2('B',b);
p3(a,b,ab); p2('AB',ab);
p3(b,a,ba); p2('BA',ba);
p4(ab,ba,c); p2('C',c);
end.

Пример работы программы:
--A--
  -4   3   2  -1  -4
   3  -4   1  -1   2
  -3  -3  -1   4  -4
   2  -1   4   2  -5
  -5  -3  -1   3   1
--B--
  -5   3  -3   0   0
   0   3   4  -5  -3
  -4   3  -4   1  -1
   4   1   1  -1  -2
  -4   2   2   0   0
--AB--
  24  -6   7 -12  -9
 -31   3 -26  22  13
  51 -25  -3  10   2
   2   7 -34   7  -5
  37 -22  12  11   4
--BA--
  38 -18  -4 -10  38
   2 -10 -18  -6  12
  44 -10   4 -16  32
  -8  12   6  -9 -15
  16 -26  -8  10  12
--C--
 -14  12  11  -2 -47
 -33  13  -8  28   1
   7 -15  -7  26 -30
  10  -5 -40  16  10
  21   4  20   1  -8