#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <stack>
#include <list>
#include <memory.h>
using namespace std;
int main() {
int input_tc;
cin >> input_tc;
for(int tc = 1; tc <= input_tc; tc++) {
double c, f, x;
double d = 2.0;
cin >> c >> f >> x;
double ans=0;
double tmp =0;
double k = 0;
while(1){
ans += x / d;
d += f;
tmp += x / d + c / (d - f);
if (ans < tmp) {
k += x / (d-f);
break;
}
ans = tmp;
k += c / (d - f);
}
printf("Case #%d: %.7lf\n", tc, k);
}
return 0;
}
