program hoandoi;

uses crt;

var a,b:real;

begin

clrscr;

write('nhap so a');readln(a);

write('nhap so b');readln(b);

write('truoc khi nhap a =',a,'b=',b);</p><p>a:=a+b;</p><p>b:=a-b;</p><p>a:=a-b;</p><p>write('sau khi nhap a=',a,'b=',b):10:2;

readln

end.

program hoandoi;

uses crt;

var a,b:real;

begin

clrscr;

write('nhap so a');readln(a);

write('nhap so b');readln(b);

write('truoc khi nhap a =',a,'b=',b);</p><p>a:=a+b;</p><p>b:=a-b;</p><p>a:=a-b;</p><p>write('sau khi nhap a=',a,'b=',b):10:2;

readln

end.