A college has a financial aid formula that applies to applicants whose family income is below a certain threshold. The financial aid can be determined by the function f(x)=20000+3000x,f(x)=20000+3000x, where xx is the number of siblings (including half-siblings and step-siblings) that the applicant has living in their household. Find and interpret the given function values and determine an appropriate domain for the function.

f(-3)=f(−3)=
, meaning a qualifying applicant with
siblings in their household would get $
in financial aid. This interpretation
in the context of the problem.
f(4)=f(4)=
, meaning a qualifying applicant with
siblings in their household would get $
in financial aid. This interpretation
in the context of the problem.
f(2.5)=f(2.5)=
, meaning a qualifying applicant with
siblings in their household would get $
in financial aid. This interpretation
in the context of the problem.
Based on the observations above, it is clear that an appropriate domain for the function is