Anna is working two summer jobs, making $18 per hour lifeguarding and making $11 per hour clearing tables. In a given week, she can work a maximum of 14 total hours and must earn at least $210. If Anna worked 12 hours clearing tables, 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.
Answer: She would make $132 a day by cleaning tables for 12 hours and getting 11 per hour. She would have to get rid of 1 hour and 90 minutes of lifeguarding to get the same pay.