9.       A restaurant that goes by the name Soft Rock Cafe is contemplating a T-shirt
advertising promotion. Monthly sales data from T-shirt shops marketing the "Barry Manilow Eats at Soft Rock" design indicate that the demand curve for the T-shirts can be described as:
Q = 4,000 - 500P where Q is T-shirt sales and P is price.         -v
a.	How many T-shirts could the cafe sell at $5 each?
b.	What price would Soft Rock have to charge to sell 2,000
T-shirts?
c.	Calculate the own price elasticity of demand when the price goes
from $5 to $4.