Should only have two terms, this means you have to combine like terms and simplify. take a look at photo.

The yard is a rectangle, and the shed is also a rectangle.
You need to find the areas of the two rectangles.
Then, subtract the area of the shed from the area of the yard.
Yard: length = 13x - 4; width = 5x
Shed: length = 2x + 4; width = 2x

Area of yard:
A = LW = (13x - 4)(5x) = 65x^2 - 20x

Area of shed:
A = LW = (2x + 4)(2x) = 4x^2 + 8x

Area of lawn = area of yard - area of shed

Area of lawn = (65x^2 - 20x) - (4x^2 + 8x)
                     = 65x^2 - 20x - 4x^2 - 8x
                     = 61x^2 - 28x

The area of the lawn is 61x^2 - 28x