Ernie's house is exactly 50 miles west of Bert's house. At noon, Bert leaves his house and drives north at a constant rate of 20 mph. At the same time, Ernie leaves his house and drives west at a constant rate of 40 mph. (a) In this scenario, is the distance between Bert and Ernie increasing or decreasing at 12:30 pm? Explain. (You don't need to calculate anything to answer this; just think about the situation.) (b) At 12:30 pm, at what rate is the distance between Bert and Ernie changing? (c) Suppose that, instead of heading west at noon, Ernie had decided to head east. In this case, what would the answer to (b) be?