How many square feet of outdoor carpet will we need for this hole?

The whole ends up being 42 ft².

Area of a triangle = 1/2 * base * height. 
So that lil triangle piece is 1/2 * 2 * 3 = 1/2 * 6 = 3

Now we do the rectangle piece. Area of a rectangle = length * width
So that rectangle is 3 * 7 = 21

If you take away those two, you are left with a trapezoid. 
Area of a trapezoid is 1/2 * (base 1 + base 2) * height
Base 1 is the width of the rectangle which is 3. Base 2 is the 6. The height is the given 11 feet minus the 7 feet from the length of the rectangle which is 4. 

Plug all this in to the formula you get 1/2 * (6 + 3) * 4 = 1/2 * 9 * 4 = 1/2 * 36 = 18.

Now add all of your areas together;

21 + 3 + 18 = 24 + 18 = 42