After graduating from college, Billy has found a job paying $42,000 a year. He wants to buy a car and needs a loan. The bank says his debt to income ratio must be less than 40%. His monthly bills are $600 for rent, $100 for utilities, $80 for his cell phone, $100 for his car insurance, and $100 for his student loans. a) What is his debt to income ratio? b) What is the maximum car payment he can have?