A can do a piece of work in 9 days. B can do the same in 12 days. In how many days can the work be completed if A and B work together?
a) 5 1/9 days
b) 5 1/4 days
c) 5 1/3 days
d) 5 1/7 days

• A's one day work=1/9
  B's one day work=1/12
  Both's one day work=1/9+1/12
  =7/36
  so they will take 36/7 days
  36/7=5 1/7
• 13 years agoHelpfull: Yes(0) No(0)
• d) 5 1/7 days
  A's one day work =1/9
  B's one day work=1/12
  (A+B)'s one day work=1/9+1/12=7/36
  time taken=36/7=5 1/7 days
• 12 years agoHelpfull: Yes(0) No(0)