To solve this problem you have to look at the three measurements (base x length x height), which are 7in, 3in, and 5in. For the top of the rectangular prism, the surface area is 21in (7in x 3in) and since the bottom is the same, the bottom is also 21in. Now that you have the top and bottom, let's look at the sides. The surface area for the long-sides is 35in (7in x 5in) and since both sides are the same, they are both 35. The surface area for the ends of the rectangular prism is 15in (5in x 3in) and since they are both the same, they are both 15in. Now that you have figured out what measurement goes with what, add all them up. (21in +21in) = 42in | (35in +35in) = 70in | (15in + 15in) = 30in
42in + (70in + 30in)
42in + 100in
The surface area for the entire shape is 142 inches.
Based on your question and based on the graph that you show. I conclude and get an answer that the vertex of the graph is (1,3) and the answer to your second question is maximum. I hope i answer your question directly