n = int(input())
for _ in range(n):
    t, mu, l = map(float, input().split())
    t = int(t * 100)
    l = int(l * 100)
    mu = int(mu * 100)
    left = 0
    right = 520000
    while right - left > 1:
        mid = (left + right) // 2
        if 25 * mid**2 + 18 * mid * t * mu <= 6480 * mu * l:
            left = mid
        else:
            right = mid
    print(f"{left/100:.2f}")