Multiple choice

A and B complete a work in 80 days and 96 days, respectively. They completed the work in 32 days with the help of C, How many days will C take to complete the entire work alone?

  1. 84

  2. 108

  3. 120

  4. 92
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A's 1 day work = 1/80, B's = 1/96. Together with C, they finish in 32 days, so combined rate = 1/32. C's rate = 1/32 - (1/80 + 1/96) = 1/32 - (12/960 + 10/960) = 1/32 - 22/960 = 30/960 - 22/960 = 8/960 = 1/120. So C alone takes 120 days.

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