Question 1083379
y=10000-500x for the first year x=12 has 4000 left
I don't know the interest in the second year, but it is on 4000 to begin with.
after 8 months, the principal would be paid off.  Depending on the interest charged, there would be less than $500 (1 more month) or less than 1000 almost certainly (2 months)
without any interest, the domain is 0<=x<=20
with interest, the domain may be expanded to 21 or even 22.