#include<stdio.h>
int main ()
{
  float s1,t1,s2,t2;
  printf("Enter the speed 1: ");
  scanf("%f",&s1);
  printf("Enter the time 1: ");
  scanf("%f",&t1);
  printf("Enter the speed 2: ");
  scanf("%f",&s2);
  printf("Enter the time 2: ");
  scanf("%f",&t2);
  
  float avgSpeed = (s1 * t1 + s2 *t2)/(t1+t2);  
  printf(" The avg speed is : %.02f\n",avgSpeed); // %.02f is for limiting the precision to 2 decimal point.
  
}