A can complete a piece of work in 7 days and B can complete the same work in 12 days. A and B worked together for 3 days. C alone completed the remaining work in 9 days. How many days will C take to complete the same work entirely?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 28.
One day work of (A + B) = (1/7 + 1/12) = 19/84
Three days work of (A + B)'= (3 × 19/84) = 19/28
Remaining work to be done = (1 - 19/28) = 9/28
Number of days in which C alone can complete the work = 28/9 × 9 = 28 days