A sports team is building a new stadium on a rectangular lot of land. The lot measures 8x by 12x and the stadium will be 3x by 6x. How much land will be left for the parking lot?
The area of the lot of land is given by length * width, or 8x * 12x = 96x^2
The area of the stadium is given by length * width, or 3x * 6x = 18x^2
The area of the parking lot left will be the difference between the area of the lot and the area of the stadium, or 96x^2 - 18x^2 = 78x^2. Answer: \boxed{78x^2}.