Câu 1 :

uses crt;

var a : array[1..100] of integer;

s, i, n : integer;

begin

clrscr;

write('nhap so luong phan tu n :');readln(n);

s := 0;

for i := 1 to n do

begin

write('nhap phan tu thu ', i ,' : ');readln(a[i]);

if (a[i] mod 3 = 0) and (a[i] mod 5 = 0) then s := s + a[i];

end;

writeln('tong :', s);

readln

end.

Câu 2 : 

uses crt;

var a : array[1..100] of integer;

i , n,  tem,  h, k : integer;

begin

clrscr;

write('nhap so n :');readln(n);

for i := 1 to n do

begin

write('nhap so nguyen thu ', i ,' : ');readln(a[i]);

end;

For h :=1 to n - 1 do

For k := h+1 to n do

If a[h] < a[k] Then

begin

tem := a[h];

a[h] := a[k];

a[k] := tem;

end;

write('day sap xep theo thu tu giam dan la :');

for h  := 1 to n do write(a[h]:8);

readln

end.