SOLUTION: A,B and C can do a piece of work together in 15 days. B alone can do in 30 days and C alone can do it in 40 days. In how many days A alone will do the work?

Question 667189: A,B and C can do a piece of work together in 15 days. B alone can do in 30 days and C alone can do it in 40 days. In how many days A alone will do the work?
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
A,B and C can do a piece of work together in 15 days.
B alone can do it in 30 days and C alone can do it in 40 days.
In how many days A alone will do the work?
:
Let a = no. of days required by A alone
let the completed job = 1
:
A typical shared work equation
:
+ + = 1
Reduce the fractions
+ + = 1
multiply by 8a, results
8(15) + 4a + 3a = 8a
120 + 7a = 8a
120 = 8a - 7a
a = 120 hrs A working alone
:
:
see if that adds up using a calc
+ + =
.125 + .50 + .375 = 1; confirms our solution
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