b1.cpp

#include <bits/stdc++.h>
using namespace std;

int main() {
  int a[50], n, k, sum = 0, cnt = 0;
  cout << "Nhap n, k: "; cin >> n >> k;
  for (int i = 0; i < n; i++) {
    cout << "Nhap a[" << i << "]: "; cin >> a[i];
    if (a[i] % k == 0) {
      sum += a[i];
      cnt++;
    }
  }
  cout << "TBC cac phan tu chia het cho K la: " << (double) sum / cnt << endl;
}