Step One
Figure out the interior angle
25 5/7 = 25.714285 repeating. The interior angle is the supplement of this angle.
180 - 25.714285 = 154.2857
The formula relating the number of sides and the interior equal angle is
interior equal angle = 180 ( 1 - 2/n) where n is the number of sides. (Google equiangular polygon to find this formula.)
154.2857 / 180 = 1 - 2/n)
0.8571428 = 6/7 = 1 - 2/n
1/7 = 2/n
n = 14 sides
This figure is regular as well as equiangular.