531 B | 531 chars
import sys
from math import sqrt, pi, sin, factorial
inp = lambda : sys.stdin.readline()[:-1].strip()
mii = lambda x = " " : [*map(int,inp().split(x))]
mfi = lambda x = " " : [*map(float,inp().split(x))]
ii = lambda : int(inp())
fi = lambda : float(inp())
p = print
def solve():
k, p, x = mii()
ans = 1000000000000000000
for m in range(1, 100000):
money = m * x + k / m * p
ans = min(ans, money)
print(f"{ans:.3f}")
if __name__ == "__main__":
tc = ii()
for t in range(1, tc+1):
solve()