Explanation:
so it starts with
182 = 182 × 3 / p
as the price is inversely related to D.
(a)
so, in general
D = 182 × 3/p = 546/p
(b)
D = 546/3.25 = 168 bags
if the price increases to $3.25, then they will sell only 168 bags.
I am sure, the function will not stay linear for every value of p. for example, if they increase the price to $546 per bag, they would still sell 1 bag. but I am certain, they would fall to 0 sold bags much, much earlier than that ...