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 Q=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?
(Use the point formula)