Q:

P and Q together can do a job in 6 days. Q and R can finish the same job in 60/7 days. P started the work and worked for 3 days. Q and R continued for 6 days to finish the work. Then the difference of days in which R and P can complete the job alone is 

• 1
  12 days
• 2
  15 days
• 3
  10 days
• 4
  8 days