Answer:
21 roads
Step-by-step explanation:
If each two cities are connected by a direct road, to find the number of roads we just need to solve a combination of 7 choose 2, that is, we need to find all pairs of two cities among the 7 cities:
Combination of 7 choose 2 = 7! / (5! * 2!) = 7*6/2 = 21
So there is a total of 21 roads on the island.
Yes you would subtract but only if your subtracted it from a negetive
