Maths Olympiad Prep

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Algebra Difficulty 3.0 AMC 10/12 Find the answer Canada

Bill and Jill are hired to paint a line on a road. If Bill works by himself, he could paint the line in BB hours. If Jill works by herself, she could paint the line in JJ hours. Bill starts painting the line from one end, and Jill begins painting the line from the other end one hour later. They both work until the line is painted. Which of the following is an expression for the number of hours that Bill works?

(A) B(J+1)B+J\dfrac{B(J+1)}{B+J} (B) J+1J+1 (C) BJB+J+1\dfrac{BJ}{B+J}+1 (D) B+J12\dfrac{B+J-1}{2} (E) B(J1)B+J\dfrac{B(J-1)}{B+J}

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Source: CEMC, University of Waterloo, licensed CC-BY-NC-4.0. Statement reproduced verbatim; metadata (topic, difficulty) added by this project. Solutions are the publisher's, linked not copied.