BT1
var a,b:longint;
begin
readln(a,b);
writeln('Tong ',a+b);
writeln('Hieu ',a-b);
writeln('Tich ',a*b);
writeln('Thuong ',a mod b);
readln; 
end.
BT2
var n:longint;
begin
readln(n);
if (n mod 2 = 0) then writeln(n,' la so chan')
 else writeln(n,' la so le');
readln;
end.
BT3
var x,y:longint;
begin
readln(x,y); 
writeln('Ket qua = ',(2*x)+(3*y));
readln
end.

BT1

uses crt;
var a,b:integer;
begin
    clrscr;
    write('Nhap a,b: ');
    readln(a,b);
    writeln('Tong: ',a+b);
    writeln('Hieu: ',a-b);
    writeln('Tich: ',a*b);
    writeln('Thuong: ',a/b:0:3);
readln;
end.

BT2 Nhập số thực chứ số nguyên thì tất nhiên nó là nguyên rồi :))

uses crt;
var n:real;
begin
    clrscr;
    write('Nhap n: ');
    readln(n);
    if frac(n) = 0 then write(n:0:0,' la so nguyen')
    else write(n:0:3,' la so le');
readln;
end.

BT3

uses crt;
var x,y:integer;
begin
    clrscr;
    write('Nhap x,y: ');
    readln(x,y);
    writeln('Ket qua: ',2*x+3*y);
readln;
end.