Graph each line.

Extend each line long enough so that a closed figure is formed when finished. 
Find where the lines intersect.
Solve the equations simultaneously to find these points.

The giraffe habitat is the enclosed quadrilateral.

From the area of the rectangle, subtract the areas of the two right triangles to find the remaining area of the quadrilateral.  These areas can be found by counting units.

Rectangle:  9 by 16 units = area of 144 sq. units
Right triangle upper left:  bases are 8 by 16 units = area of 64 sq. units.
Right triangle lower right:  bases are 9 by 9 units = area of 40.5 sq. units.

Area of quad. = Area of rect. - Area tri. - Area tri.
         x           =       144        -    64      -  40.5
         x           =      39.5 square units.