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