There are 540 degrees in a pentagon, and we have three right angles. Three right angles measures 270 degrees, half of 540. So we have 270 degrees left, and we divide it by two since the angles are equal and get 135 degrees.
there are 3 triangles in the picture. each equals 180, 180 times 3 is 540. 540 - 180 (90*3 which is how many right angles are in the picture) is 360. 360 divided by 2 is 180.
