Answer:
I would say 5 kg because you get more kg with a little bit more money added
I believe that it's A neither, because I don't think that it could be displayed on a coordinate graph when it has an exponent in it. So I think it's A. Let me know if I'm correct. ;-)
Answer:
2 2/3 as an improper fraction is 8/3
8/3 × 1/4 = 2/3
Make a change of coordinates:


The Jacobian for this transformation is

and has a determinant of

Note that we need to use the Jacobian in the other direction; that is, we've computed

but we need the Jacobian determinant for the reverse transformation (from

to

. To do this, notice that

we need to take the reciprocal of the Jacobian above.
The integral then changes to

Since A = bh
and A = 198 and b = 18?
h = A/b
= 198/18
= 11