import heapq

def dijkstra(adj, start):
    dist = {node: float('inf') for node in adj}
    dist[start] = 0
    heap = [(0, start)]
    while heap:
        d, node = heapq.heappop(heap)
        if d > dist[node]:
            continue
        for neighbor, edge_weight in adj[node]:
            new_dist = d + edge_weight
            if new_dist < dist[neighbor]:
                dist[neighbor] = new_dist
                heapq.heappush(heap, (new_dist, neighbor))
    return dist

def solve_case(west_stations, east_stations, overpass_options):
    # Build the initial graph
    graph = {i: [] for i in range(1, west_stations + east_stations + 1)}
    for i in range(1, west_stations):
        graph[i].append((i+1, 1))
        graph[i+1].append((i, 1))
    for i in range(1, east_stations):
        graph[west_stations+i].append((west_stations+i+1, 1))
        graph[west_stations+i+1].append((west_stations+i, 1))
    overpass_weights = {}
    for i, (west, east) in enumerate(overpass_options):
        weight = dijkstra(graph, west)[east]
        overpass_weights[i] = weight
        graph[west].append((west_stations+east, weight))
        graph[west_stations+east].append((west, weight))
    # Solve each overpass option
    ans = []
    for i, (west, east) in enumerate(overpass_options):
        graph[west].remove((west_stations+east, overpass_weights[i]))
        graph[west_stations+east].remove((west, overpass_weights[i]))
        dist = dijkstra(graph, 1)
        total_dist = sum(sum(dist.values()) - v for v in dist.values())
        avg_dist = total_dist / (west_stations * east_stations)
        ans.append(avg_dist)
        graph[west].append((west_stations+east, overpass_weights[i]))
        graph[west_stations+east].append((west, overpass_weights[i]))
    return ans

# Parse input and solve each test case
t = int(input())
for i in range(1, t+1):
    w, e, c = map(int, input().split())
    overpass_options = [tuple(map