The shape of the house is not specifically mentioned here so I assume that it has a conventional shape like that of a rectangular prism. A rectangular prism is like a shoe box, that has two bases, the one on top and at the bottom and 4 lateral sides. The volume of a rectangular prism is equal to
V = Area of base * Height
The area of base is also rectangular because of the given length of 50 ft and a width of 26 ft. Thus, the area of the rectangular base is
Area of base = 50 ft * 26 ft = 1,300 ft²
Then, we use the height which is equal to 8 ft to finally determine the volume.
Volume = (1,300 ft²)(8 ft)
Volume = 10,400 ft³