At first you need to take its lateral surface area by using the perimeter of base of the triangle and the height of prism.
Then after calculating it you need to find out its total surface area which is asked in the question and that is calculated by adding the area of both triangles of the prism in the lateral surface area.
6 3/10 divided by 5 1/4 is 1.2. So 6 3/10 is 1.2 times more than 5 1/4. We then take the 1.2 and multiply it by 2 hours because we need to find what's 1.2 times more than 2 hours. So then you get 2.4 hours.
