Suppose the Quantity Demanded Weekly of the Super Titan Radial

Multiple Choice

Suppose the quantity demanded weekly of the Super Titan radial tires is related to its unit price by the equation where p is measured in dollars and x is measured in units of a thousand. How fast is the quantity demanded changing when x = 13, p = 73, and the price/tire is increasing at the rate of $6/week?

A) Dropping at the rate of 278 tires/wk.
B) Dropping at the rate of 231 tires/wk.
C) Dropping at the rate of 226 tires/wk.
D) Dropping at the rate of 268 tires/wk.