Not sure why, but I wasn't able to post my solution as text, so I've written it elsewhere and am posting screenshots of it here.
In the fifth attachment, the first solution is shown above the second one.
Answer:

Step-by-step explanation:
Let
w------> the weight in pounds
we know that
A delivery company charges an extra fee for a package that weighs more than 100 pounds
so
For
-----> the company charges an extra fee
therefore
For
----> the company not charge an extra fee
F(x)=10 would be the easiest way to put that
Yes, as x(y) increase when y(x) increases , they are proportional.
2(5)^2+10
2(25)+10
50+10
60
Yes