You Have Been Hired as a Marketing Consultant to Big $q = m p + b$

You have been hired as a marketing consultant to Big Book Publishing, Inc., and you have been approached to determine the best price for the hit calculus text by Whiner and Istanbul entitled Fun with Derivatives. You decide to make life easy and assume that the demand equation for Fun with Derivatives has the linear form $q = m p + b$
Where p is the price per book, q is the demand in annual sales, and m and b constants are certain constants you'll have to figure out. Your market studies reveal the following sales figures: when the price is set at $57 per book, the sales amount to 12,280 per year, when the price is set at $86 per book, the sales drop to 4,740 per year. Use these data to calculate the demand equation.

A) $q = 57 p - 271$
B) $q = 260 p$
C) $q = - 86 p + 260$
D) $q = 86 p - 2,540$
E) $q = - 260 p + 27,100$