Takeshi-san and Elizabeth-san are TIU graduates majoring in Economics. They find several economic problems as follows (total 10 points): a) They read the supply schedule and the supply curve. They need to explain: How are they related? Why does the supply curve slope upward? (3.5 points) b) They document that business travelers and vacationers have the following demand for airline tickets from Tokyo to Osaka: Quantity Demanded Quantity Demanded Price (business travelers) (vacationers) JPY 20,000 2,000 800 JPY 25,000 1,900 600 As the price of tickets rises from JPY 20,000 to JPY 25,000 what is the price elasticity of demand for business travelers and vacationers? Use the midpoint method in your calculations! (3.5 points) c) According to Otaki et al. (2017), how the welfare economics change in the Tokyo Metropolitan Expressway? Explain! (3 points)