Final answer:
The perimeter of quadrilateral ACKB is 74 feet.
Step-by-step explanation:
In an equilateral triangle, all sides are equal. Since AB is given as 18.5 feet, all sides of the equilateral triangle ABC are also 18.5 feet.
For the perimeter of quadrilateral ACKB, we need to find the length of CK and KB. Since CK and KB are opposite sides of the equilateral triangle ABC, they are also equal in length. Therefore, CK = KB = 18.5 feet.
The perimeter of quadrilateral ACKB is the sum of all the sides: AC + CK + KB + BA. Since AC and BA are equal to 18.5 feet, the perimeter is 2 * 18.5 + 18.5 + 18.5 = 74 feet.