At the price of $100, tourists demand 267 airplane tickets. At the same price, business travelers demand 237. At the price $110, tourists demand 127 tickets and business travelers demand 127. Assuming that the demand curves of business travelers and tourists are both linear over this price range, what is the price elasticity of demand at the price $100?
answer: -0.05
I need to know why the answer is -0.05. how to solve it?