math
posted by Bud .
You have just opened a new nightclub, Russ' Techno Pitstop, but are unsure of how high to set the cover charge (entrance fee). One week you charged $9 per guest and averaged 160 guests per night. The next week you charged $11 per guest and averaged 140 guests per night.
(a) Find a linear demand equation showing the number of guests q per night as a function of the cover charge p.

q = ap+b
160 = 9a+b
140 = 11a+b
a = 10
b = 250
q = 250  10p