I assume that the total length of the oval includes the semicircular ends. The radius of the semicircles is half the width=12/2=6 in. The overall length is the length of the straight section plus two radii. So the rectangular central portion has a length of 18-12=6. The area of this rectangle is 6×12=72 sq in.
Put the semicircular ends together to form a circle of radius 6, area 36π sq in. So the total area is 72+36π=185.1 sq in approx.
