Nyesha owns a lawn service company. Currently it takes her 50 hours a week to service all of her customers. To reduce the number of hours a week she needs to work, Nyesha hires Shantese to help her. While Nyesha was on vacation, Shantese was able to complete all of the work in 60 hours. If Shantese and Nyesha work together, after Nyesha returns from vacation, how long will it take them to service all their customers?