You are trying to figure out how to spend your summer. You have two options for jobs. Babysitting (b) pays $12 an hour and cleaning houses (c) pays $15 an hour. You would like to make sure you make at least $420 per week. If you work 32 hours cleaning, how many hours do you need to work babysitting to get $420 for the week? If you work 10 hours babysitting, how many hours do you need to work (at least) cleaning houses to reach your goal?