joey dropped his phone and his screen cracked. His parents are making him pay for its repair. The cost of the repair is at least $150. In order to cover this bill, Joey has started babysitting for $10 per hour and working part-time at Trader Joe's for $15 per hour. He can work at most 20 hours a week. How many hours could he work at each job to earn the money he needs in the time he has?