1.
const n=5;
var a : array[1..n,1..n] of integer;
    sum,k,i,j : integer;
begin
Randomize; 
for i:=1 to n do
 begin
  for j:=1 to n do
   begin
   a[i,j]:=random(20)-10; 
   write(a[i,j]:4); 
  end;
  writeln;
  end; 
sum:=0; k:=0;
for i:=2 to n do 
  for j:=1 to i-1 do
   begin
    sum:=sum+a[i,j]; 
    k:=k+1
   end;
writeln('sum = ',sum); 
writeln('Среднее = ',sum/k);
end.
----------------------------
2.
const n=4; m=5;
var a : array[1..n,1..m] of integer; 
    sum,i,j : integer;
begin
Randomize; 
for i:=1 to n do
 begin
  for j:=1 to m do
   begin
   a[i,j]:=random(20)-10; 
   write(a[i,j]:4);    
  end;
  writeln;
  end; 
sum:=0;
for i:=1 to n do 
  for j:=1 to m do
   if a[i,j]<0 then sum:=sum+a[i,j]; 
writeln('sum = ',sum); 
end.