Mark and Rachel both work for Smith Landscaping Company. Mark can finish a planting job in 5 hours,

Mark and Rachel both work for Smith Landscaping Company. Mark can finish a planting job in 5 hours, while it takes Rachel 3 hours to finish the same job. If Mark and Rachel will work together on the job, and the cost of labor is $50 per hour, what should the labor estimate be? (Round to the nearest cent, if necessary.) how do i do this