Michelle has $15 and wants to buy a combination of dog food to feed at least four dogs at the animal shelter. A serving of dry food costs $1, and a serving of wet food costs $5. Part A: Write the system of inequalities that models this scenario. (5 points) Part B: Describe the graph of the system of inequalities, including shading and the types of lines graphed. Provide a description of the solution set. (5 points)