#include <cassert>
#include <cmath>
#include <algorithm>
#include <iostream>
#include <iomanip>
#include <climits>
#include <map>
#include <queue>
#include <set>
#include <cstring>
#include <vector>

using namespace std;
typedef long long ll;

ll to_ll(string str){
  int len = str.length();
  return stol(str.substr(0, len - 3)) * 100+(str[len - 2] - '0') * 10 + (str[len - 1] - '0');
}

int main() {
  int N;
  cin >> N;

  for (int i = 0; i < N; ++i) {
    string T, U, L;
    cin >> T >> U >> L;

    ll ok = 0;
    ll ng = 520000;
    ll t = to_ll(T);
    ll u = to_ll(U);
    ll l = to_ll(L);

    while (abs(ok - ng) >= 2) {
      ll v = (ok + ng) / 2;
      ll len = v * (25 * v + 18 * t * u);

      if (len <= l * 6480 * u) {
        ok = v;
      } else {
        ng = v;
      }
    }

    cout << fixed << setprecision(2) << floor(100 * ok) / 10000 << endl;
  }

  return 0;
}