Is my set up right? \n\n\n1. If Amy, Bianca and Carrie work together on a job, it will take one and one-third hours. If only Amy and Bianca work, it would take one and five-sevenths hours, but if Bianca and Carrie work, it would take two and two-fifths hours, how long would it take each girl working alone to complete the job?\n\nThis looks like three equations in three unknowns. \n\n\nAmy = 1/x\nBianca = 1/y\nCarrie = 1/z\n\n1/x + 1/y + 1/z = 4/3\n1/x + 1/y = 12/7\n1/y + 1/z = 12/5\n\nYes?\n\n\n2. John can paint a garage in 8 hours. Gary can do it in 6 hours. Fred can do it in 4 hours. How long will it take if they all paint together?\n\nJohn = 1/8\nGary = 1/6\nFred = 1/4\n\n1/8 + 1/6 + 1/4 = 1/x\n\nLet x = length of time it will take all three to do the job.