Kristin earns $7 per hour at a video store and $10 per hour at a landscaping company. she must work at least 4 hours per week at the video store, but the total number of hours she works at both jobs cannot be greater than 15. a. let v represent the number of hours working at the video store and l represent the number of hours working at the landscaping company. write a system of inequalities to represent the number of hours worked in one week. b. determine kristin's maximum weekly earnings.