Answer:
83.4
Explanation:
Area of a Regular Polygon: L (of side) times apothem (height) x 1/2 
L : 13.9 
Looking at the triangle we can assume the height would be 12 since its logical that 3 of the 4 lines can fit in the middle of the triangle. 
H: 12 
13.9 x 12 = 166.8 
166.8/2 = 83.4