https://omegaup.com/arena/problem/Abduciendo-vacas
#include <stdio.h> 
 
int main( ) { 
   float v, e, d; 
   scanf("%f%f%f", &v, &e, &d); 
   float t = (-e * d) / (v - e); 
   printf("%f", t); 
   return 0; 
}