Plz math. a and b are question not answers

Notice the cut off sections.
You can see the cut off sections form two separate triangles.

So, for the bottom triangle, it's base is of the length (24 - 14) ft and its height is of the length (11 - 7) ft.
You can repeat the same for the top triangle (11 - 6) ft in height, and (24 - 20) ft in length.

To find the area, you will need to find the area of the rectangle, that is, the area of the hexagon with the triangles, and then subtract the areas of the triangle.