Joseph is working two summer jobs, making $12 per hour babysitting and making $6 per hour walking dogs. In a given week, he can work at most 9 total hours and must earn at least $90. If Joseph worked 2 hours babysitting, determine all possible values for the number of whole hours walking dogs that he must work to meet his requirements. Your answer should be a comma separated list of values. If there are no possible solutions, submit an empty answer.