Looks like you are screwed good luck:)
It has a minimum value at x = 3 and f(x) = 4
Vertex form is
f(x) = a(x - 3)^2 + 4 where a is some constant to be found
From the graph when x = 5 f(x) = 15, so
15 = a * 2^2 + 4
a = 15-4/4 = 11/4
so our equation is f(x) = 11/4(x - 3)^2 + 4
five pairs of jeans should cost $67.5
Y= k/x
When y=42, x=6
42= k/6
k= 42x6
=252
When x=9,
y= 252/9
= 28
