Answer:
1) It may not be fair to Kara,but since many teenagers are ill-responsible, it may be best to work out deals with their parents, rather than a child. Since she is supposed to be making monthly payments, that may mean that she forgets, or doesn't do so. By having a parent there, Kara and the manager can ensure that there is understandment about the product that is being sold.
2) Kara is under 18, which means that a salesperson does not have to sell her a product if they feel it is not fit for them. So no, it is not illegal or discriminatory to her race, but perhaps to her age group..
3) a. The manager may be worried that Kara is not mature or old enough to have the responsibilities that come with paying a month-to-month rate.
b.The manager also may be worried that Kara took the money from her parents to secretly buy the computer, rather than buying the computer with her own money.
I hope this helps & Good Luck!