1. **State the problem:** We need to find the perimeter $p$ of an irregular L-shaped polygon with four right angles and sides measuring 2.5 ft., 1.25 ft., 1.25 ft., and 2.5 ft. 2. **Recall the perimeter formula:** The perimeter of a polygon is the sum of the lengths of all its sides. 3. **Identify all sides:** The polygon has 8 sides in total because it is an L-shape with four right angles. The given sides are 2.5 ft., 1.25 ft., 1.25 ft., and 2.5 ft. The other four sides are equal to these because opposite sides in the L-shape correspond. 4. **Calculate the perimeter:** $$p = 2.5 + 1.25 + 1.25 + 2.5 + 2.5 + 1.25 + 1.25 + 2.5$$ 5. **Simplify the sum:** $$p = (2.5 + 2.5 + 2.5 + 2.5) + (1.25 + 1.25 + 1.25 + 1.25) = 10 + 5 = 15$$ 6. **Final answer:** $$p = 15 \text{ ft}$$ The perimeter of the L-shaped polygon is 15 ft.