When working together, Arthur and Bea can complete a job in 4 hours. Arthur and Chester can complete the same job in 5 hours. Bea and Chester can complete the same job in 6 hours. How will it take all 3 people working together?
+37159 1 /(a+b) = 4 and 1/ (a+c) = 5 and 1/(b+c) = 6
4a+4b=1 5a+5c=1 6b + 6c =1
a = 1/4-b a = 1/5-c c = 1/6-b
1/4-b = 1/5 -c
1/4-b = 1/5 - 1/6+b
1/4 -1/5+1/6 = 2b
b = 13/120 then a = 17/120 and c = 7/120
1/ ( 17/120 + 13/120 + 7/120) = x
x = 3.24 hours
Is there a EASIER way to do this problem???? 
