#include <stdio.h>

int main(){

  int nbk, poids, age, l_corne, h_garrot, note;

  scanf("%d", &nbk);

  for(int i = 1; i<=nbk; i++){

    scanf("%d", &poids);
    scanf("%d", &age);
    scanf("%d", &l_corne);
    scanf("%d", &h_garrot);

    note = l_corne*h_garrot+poids;
    printf("%d\n", note);
  }
}