Ravi can do a piece of work in 30 days while Prakash can do it in 40 days. In how many days will they finish it together?
Choose one
A) 17 1/7 days	B) 17 1/8 days	C) 17 1/9 days	D) 17 7/7 days	E) 18 1/7 days
1/30 + 1/40 = 7/120   120/7   = 17 1/7 days   17 1/7 daysnswer: 17 1/7 days
<result>A</result>
Ravi can do a piece of work in 30 days while Prakash can do it in 40 days. In how many days will they finish it together?