What was the supreme court case engel v. vitale.

Engel v. Vitale was a landmark in the United States Supreme Court case that ruled its unconstitutional for state officials to compose an official school prayer and to encourage its recitation in public schools.

https://en.wikipedia.org/wiki/Engel_v._Vitale

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