Rhoda takes a job with a construction company. She earns $5 an hour for the first 40 hours of each week and then gets "double-time" for overtime. That is, she is paid $10 an hour for every hour beyond 40 hours a week that she works. Rhoda has 70 hours a week available to divide between construction work and leisure. She has no other source of income, and her utility function is U = cr where c is her income to spend on goods and r is the number of hours of leisure that she has per week. She is allowed to work as many hours as she wants to. How many hours will she work? Please show work! The answer is 45.