To find the area of the shaded region we need to divide it into one triangle and two rectangles like you can see in the picture.
The area of a triangle is

, and we know from our figure that our triangle has base=10 feet and height=5 feet, so:


The area of a rectangle is

. We have tow rectangles in our figure, so for our first one:


for our second one:


Now that we have the areas of all out figures, lets add them to find the area of the shaded region:


We can conclude that the area of the shaded region is
51 square feet.