The equation for a demand curve has been estimated to be Q=100 - 10P + 0.5Y Where Q is quantity, P is price, and Y is income. Assume P=7 and Y=50. A) At a price of 7, what is price elasticity? B) At an income level of 50, what is income elasticity? C) Now assume income is 70. What is the price elasticity at P=8?
(*On a- I need to know HOW you get -10 within the equation!)