Annabelle is working two summer jobs, making $10 per hour babysitting and making $20 per hour lifeguarding. In a given week, she can work no more than 19 total hours and must earn no less than $290. If Annabelle worked 3 hours babysitting, determine the minimum number of whole hours lifeguarding that she must work to meet her requirements. If there are no possible solutions, submit an empty answer.