The number of units sold is dependent on the price
starts at 24 with price 8
as price rises by 1 units goes down by 3
units sold then becomes (24 - 3(x-8) ) = 48 - 3x
PROFIT is number of units sold * price - units sold * cost
(48-3x) * x - (48-3x) * 4 <=====simplify this
-3x^2 + 48x -192 + 12x
a) PROFIT = -3x^2 + 60x - 192
b) Max occurs at - b/2a = -60 / (-3*2) = 10 dollars price
c ) -3(10^2) + 60(10) - 192 = 108 dollars profit