P can do piece of work in 30 days while Q alone can do it in 40 days. In how many days can P and Q working together do it?
Choose the correct answer:
A) 17 1/7
B) 18 1/7
C) 20 1/7
D) 22 1/7
E) 24 2/7
P D17 1/7YS WORK = 1/30   Q ONE D17 1/7Y WORK = 1/40   (P+Q) ONE D17 1/7Y = 1/30 + 1/40 = 7/120   17 1/7 17 1/7ND B FINISH WORK = 17 1/7 D17 1/7YS   17 1/7NSWER 17 1/7
<result>A</result>
P can do piece of work in 30 days while Q alone can do it in 40 days. In how many days can P and Q working together do it?