program bai_1;
uses crt;
var a,b,cv,dt:longint;
begin
 clrscr;
  write('nhap chieu dai:');readln(a);
  write('nhap chieu rong:');readln(b);
  cv:=(a+b);
  dt:=a*b;
  writeln('dien tich la:',dt);
  write('chu vi la:',cv);
 readln;
end.

---------------------------------------------------

program bai_2;
uses crt;
var a,cv,dt:longint;
begin
 clrscr;
  write('nhap 1 canh:');readln(a);
  cv:=a*4;
  dt:=a*a;
  writeln('dien tich la:',dt);
  write('chu vi la:',cv);
 readln;
end.

-------------------------------------------

program bai_3;
uses crt;
var a,b,h:longint;dt:real;
begin
 clrscr;
  write('nhap day lon:');readln(a);
  write('nhap day be:');readln(b);
  write('nhap chieu cao:');readln(h);
  dt:=(a+b)/2*h;
  writeln('dien tich la:',dt);
 readln

end.

-------------------------------------------------

program bai_4;
uses crt;
var a:array[1..4]of longint;i:longint;tong:real;
begin
 clrscr;
  tong:=0;
  for i:=1 to 4 do
        begin
         write('nhap so thu',i,':');readln(a[i]);
         tong:=tong+a[i];
        end;
  tong:=tong/4;
  writeln('trung binh cong cua bon so do la:',tong);
 readln;
end.

---------------------------------------------------------

program bai_5;
uses crt;
var a,b,tam:longint;
begin
 clrscr;
  write('a=');readln(a);
  write('b=');readln(b);
  tam:=a;
  a:=b;
  b:=tam;
  writeln;
  writeln('a=',a);
  write('b=',b);
 readln;
end.

đây á bạn cho mình xin hay nhất ạ