What angle in 25 gon?

The sum of the interior angles of a n-gon is (n-2)*180 degrees.

So the sum of the int angles of a 25-gon is 23*180 = 4140 degrees.

If the 25-gon is regular, then each of its interior angles is equal. In this case, it is 4140/25 = 165.6 degrees.