#int(input())
#map(int, input().split())
#list(map(int, input().split()))

# N = int(input())

# T = [0] * N
# for i in range(N):
#     # T[i] = list(map(float, input().split()))
#     T[i] = input().split()

# for i in range(N):
#     for j in range(3):
#         s = T[i][j]
#         T[i][j] = int(s[:-3]) * 100 + int(s[-2:]) * 1

# def S(v, t, m, l):
#     v *= 1000 / 3600
#     return (v * t * 20 * m) + (v * v) - (l * 20 * m)
# print(S(57.26, 0.75, 0.70, 30.00))
# print(S(5726, 75, 0.70, 3000))

# # print(T)

# for i in range(N):
#     t = T[i][0]
#     m = T[i][1]/100
#     l = T[i][2]
#     # print(t, m, l)

#     vmax = 520000
#     vmin = 0

#     while vmax - vmin > 1:
#         h = (vmax + vmin) // 2
#         if S(h, t, m, l) > 0:
#             vmax = h
#         else:
#             vmin = h

#     # print(format(int(vmin*100)/100, ".2f"))
#     # print(vmin)
#     # print(vmin)

#     c, d = divmod(vmin, 100)
#     print(str(c) + "." + format(d, "02d"))

N = int(input())

T = [0] * N
for i in range(N):
    T[i] = list(map(float, input().split()))

def S(v, t, m, l):
    v *= 1000 / 3600
    return v * t * 20 * m + v * v - l * 20 * m

# print(T)

for i in range(N):
    t = T[i][0]
    m = T[i][1]
    l = T[i][2]

    vmax = 5200
    vmin = 0

    while vmax - vmin > 0.001:
        h = (vmax + vmin) / 2
        if S(h, t, m, l) > 0:
            vmax = h
        else:
            vmin = h

    print(format(int(vmin*100)/100, ".2f"))