Question

A and B can complete a work in 12 days . However A had to leave a few days before it completed . And hence it took 16 days in all to complete the task . If A alone could complete the work in 21 days . How many days before the work gettinh over did A leave ?

Answer 1

Answer:

B can alone do the work =

1/ (1/12 -1/21)

1/B .......= 7-4/84=3/84 = 1/28

B......28 DAYS

Let A worked X days

So

Work done by A + Work done by B =1

X/21 +16/28 =1

X/21 = 12/28

X=9

A worked for 9 days means A left work before ( 16-9=) 7 days of completion

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