Q13 A train ticket from London to Berlin costs $120, then rises to f160. At the same time demand for flights from London to Berlin rises from 1500 to 2500. a) What is the definition of elasticity? List and describe the four main types of elasticity. (4 marks) b) Using the information given in the question, calculate the cross elasticity of demand for flights. Show your calculation process clearly. (3 marks) c) What does your answer to b) tell you about the relationship between the two products? Explain your answer in detail