Написать программу для решения системы линейных уравнений (Visual Basic)

1)
uses crt;
const n=8;
var i:integer;
a:array[1..n] of integer;
begin
writeln('Input elements.');
for i:=1 to n do
read(a[i]);
for i:=1 to n do
if a[i]<0 then
write(a[i],' ');
end.
2)
uses crt;
const n=10;
var i,t:integer;
a:array[1..n] of integer;
begin
randomize;
t:=0;
write('Массив: ');
for i:=1 to n do
begin
a[i]:=random(10,1);
write(a[i],' ');
if a[i] mod 2=0 then
t:=t+1;
end;
writeln(#13#10,t);
end.
3)
uses crt;
const n=10;
var i,sum,t:integer;
a:array[1..n] of integer;
begin
randomize;
sum:=0;
t:=0;
write('Массив: ');
for i:=1 to n do
begin
a[i]:=random(10,1);
write(a[i],' ');
if a[i] mod 2=0 then
sum:=sum+a[i]
else
t:=t+1;
end;
writeln(#13#10,sum,' ',t);
end.
4)
uses crt;
const n=10;
var i:integer;
a:array[1..n] of integer;
begin
randomize;
for i:=1 to n do
begin
a[i]:=random(10,1);
write(a[i],' ');
if a[i] mod 2=0 then
a[i]:=2*a[i]
else
a[i]:=3*a[i];
end;
write(#13#10);
for i:=1 to n do
write(a[i],' ');
end.

//Как-то громоздко получилось, но я так вижу. Эх, выходные.
const n=5;
var a:array[1..n] of integer;
b:array[0..8] of integer;
ar:array[1..n] of integer;
i,c,j:integer;
begin
randomize;
writeln('Array:');
for i:=1 to n do
begin
a[i]:=random(8);
write(a[i]:4);
end;
for i:=1 to n do
 begin;
  for j:=0 to 8 do
    if a[i]=j then inc(b[j]);
 end;
for i:=1 to n do
 begin;
  for j:=0 to 8 do
   if (b[j]>1) and (a[i]=j) then a[i]:=9;
 if a[i]<>9 then
  begin;
   inc(c);
   ar[c]:=a[i];
  end;
 end;
 writeln;
 for i:=0 to 8 do writeln(i,'=',b[i]);
writeln;
writeln('Final array:');
for i:=1 to n do
if a[i]=9 then a[i]:=0;

for i:=1 to c do
begin;
 a[i]:=ar[i];
 write(a[i]:4);
end;
end.