For the Following, Try to Come Up with an Additional

Essay

For the following, try to come up with an additional premise that will turn the passage into a deductively valid or an inductively strong argument. Usually this requires adding a general moral principle and, sometimes, an extra nonmoral claim as well. The idea is to guarantee that the "ought" claim follows from the "is" claim.
Karen and Gina were roommates for about five months, and, as far as Gina knew, they had planned to room together until the end of the school year. But when Gina returned from a weekend at her parents', Karen had moved out. Since she couldn't find a new roommate on such short notice, Gina asked Karen to pay half of the next month's rent, but Karen answered that she didn't owe the rent since she wasn't living there anymore. I think Karen should pay at least half of one month's rent, since Gina was led to believe Karen was going to be living there and paying half.