Answer:

unit rate is similar to speed / velocity:

[<em>unit</em><em> </em><em>rate</em><em> </em><em>must</em><em> </em><em>have</em><em> </em><em>units</em><em> </em><em>including</em><em> </em><em>per</em><em> </em><em><</em><em>time</em><em>></em><em> </em>]
250+x might be the right answer because of 250 PLUS the current balance so the current balance would stand for x
Answer:
I believe it's the last one.