If the exterior angle is 25o then the interior angle is its supplement.
The interior angle = 180 - 25 = 155 degrees. All angles are equal in the interior.
The sides aren't.
I'm hoping you get an answer besides mine. I can take you so far.
The formula for an interior angle is
180(1 - 2/n) = Interior angle. When you solve this you get
180(1 - 2/n) = 155
1 - 2/n = 155/180
1 - 2/n = 0.86111111
- 2/n = 0.8611111 - 1
2/n = 0.13888888
2 / 0,1388888 = n
n = 14.4
You can google equiangular polygon theorem to see where I got the formula. The problem is that I really don't know how to interpret the answer. It looks like you have 14 conguent sides and 1 that is 0.4 left over. The figure might still be equiangular.