They gave you the length of the two sides of the triangular part. Calculate the circumference of the semi circle on top.
Circumference of a semi circle is 1/2 x 2 x radius x PI
The radius is given as 3 ft.
Circumference = 1/2 x 2 x 3 x 3.14 = 9.42ft
Perimeter is the length of the circumference of the semi circle plus the side lengths of the triangle:
5 + 5 + 9.42 = 19.42 feet
Answer: 19.42 feet