Berbatov wrote:

Working alone at a constant rate, Alan can paint a house in a hours. Working alone at a constant rate, Bob can point 1/4 of the same house in b hours. Working together, Alan and Bob can paint 1/3 of the house in c hours. What is the value of b in terms of a and c?

a) (3ac)/(a+c)

b) (4a-12c)/(3ac)

c) (3ac)/(4a-12c)

d) (ac)/(a+2c)

e) (ac)/(a+c)

Alan's rate= 1/a

Bob's rate= 1/(4b)

Combined rate= 1/(3c)

\frac{1}{a}+\frac{1}{4b}=\frac{1}{3c}Upon solving:

b=\frac{3ac}{4a-12c}Ans: "C"

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~fluke

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