The sum of angles at a point is 360

1
The sum of angles at a point is 360, and 360 -
108 - 90 - 90 72
The sum of the angles in a pentagon is 540
So the triangle is not equilateral
Therefore angle ABC 108
The pentagon is regular, so each angle is 540 ?
5 108
Therefore angle GBH 72
Each square has four right angles, so angle ABG
angle CBH 90