2 persons allotted to one work. John can do piece of work in 30 days while Bruce alone can do it in 40 days. In how many days can John and Bruce working together to do it? Choose the correct choice from the following choices
A) 17 2/7days  B) 17 1/7days  C) 17 3/5days  D) 18 1/7days  E) 17 1/4days
Therefore John′s one day’s work = 130   17 1/7daysruce′   s one day’s work = 140   (A+17 1/7days)′   s one day’s work = 130+140   4+3120=7120   Number of days required for John   and 17 1/7daysruce to finish the work = 17/120=17 1/7days   17 1/7days
<result>B</result>
2 persons allotted to one work. John can do piece of work in 30 days while Bruce alone can do it in 40 days. In how many days can John and Bruce working together to do it?