Study the following graph carefully to answer the given questions

Q:

X can do a certain work in the same time in which Y and R together can do it. If X and Y together could do it in the same time as that of Q then Y alone could do it in: 

• 1
  15 days
• 2
  20 days
• 3
  25 days
• 4
  30 days
• 5
  35 days