#include<iostream>
#include<iomanip>
#include<fstream>
using namespace std;
ifstream in("sda.in");
ofstream out("out.out");
int n;
double C,F,X,S=2,t1,t2,T=0,G=-1;
int main()
{
	in>>n;
	out<<fixed<<setprecision(9);
	in>>fixed>>setprecision(9);
	for(int i=1;i<=n;i++)
	{
		in>>C>>F>>X;
		T=0;
		S=2;
		G=-1;
		while(G==-1)
		{
			t1=X/S;
	        t2=X/(S+F)+C/S;
	        if(t2<t1)
	        {
		T+=t2-(X/(S+F));
		S+=F;
	        }
	else
	{
		G=T+t1;
	}
		}
		out<<"Case #"<<i<<": "<<G<<"\n";
	}
}