The area of the square = side x side
The area of the triangle = 1/2 x base x height
From the given figure
The back of the dog house is made from a square of side length 2.5 feet,
and a triangle of base = the side of the square = 2.5 feet
The height of the back is 4 ft, it is equal to the side of the square + the height of the triangle
Then 2.5 + height of the triangle = 4
Then the height of the triangle = 4 - 2.5 = 1.5 feet
Now we can find the area of the square and the area of the triangle
Area of the square = 2.5 x 2.5 = 6.25 square feet
Area of the triangle = 1/2 x 2.5 x 1.5 = 1.875 square feet
Add them to find the area of the back of the dog house
The area of the back = 6.25 + 1.875 = 8.125 square feet
Round it to the nearest tenth
The area of the back = 8.1 square feet