Kali is selling two different kinds of soup - tomato soup and clam chowder. She has a total of 80 bowls, so she can sell no more than 80 bowls of soup. Each tomato soup sells for $5 and each clam chowder sells for $10. In order to reach her goal, Kali must make at least $500.
If the solution region represents the number of bowls of soup Kali needs to sell in order to reach her goal, which graph's shaded area represents the solution region?