Answer:
$9
Explanation:
f(x) = - 25 ( x - 9 )² + 200
when x = 5 ,
f(5) = - 25 ( 5 - 9 )² + 200 = - 200
when x = 9 ,
f(9) = - 25 ( 9 - 9 )² + 200 = 200
when x = 10 ,
f(10) = - 25 ( 10 - 9 )² + 200 = 175
when x = 15 ,
f(15) = - 25 ( 15 - 9 )² + 200 = -700
∴ when price = $9
the company receive the maximum profit