B4. (8 marks) a. (5 marks) Consider the following form of the gravity equation: 2 X Y25 x Y 2.5 Tuj = D.1.5 Suppose that Babylon's GDP is two times Carthage's GDP, but the distance between Babylon and Athens is three times the distance between Carthage and Athens. Which would be larger: the trade volume between Athens and Babylon, or the trade volume between Athens and Carthage, and by how many times? b. (3 marks) How has the recent COVID-19 pandemic affected the overall world trade? Answer using the gravity model