As a result of the peloponnesian war sparta was

As a result of the Peloponnesian war Sparta was the new leading power of Greece. Although the Peloponnesian Wars took some time to end, Sparta refused to destroy Athens and to enslave it's citizens, which was what Thebes and Corinth were planning to do. Athens, which had previously been strong, was now ruling almost as a subject to the other city-states and the peloponnesian war completely reshaped ancient Greece, with Sparta coming out as the strongest city-state.

Use the formula: (n-2)×180, where n is the number of sides(18-2)×180= 28800, now this is the full exterior angle of 18-gon so you divide it by 18.28800÷18=160