Pooja is twice as efficient as Aarti and takes 90 days less than Aarti to complete the job. Find the time in which they can finish the job together.  Choices:
A) 30 days  B) 45 days  C) 60 days  D) 90 days  E) None of these
EXPLANATION:   Hint:   Assume that Pooja completes the job in 'x' days.   So, Aarti will take '2x' days to complete the same job.   As Pooja takes 90 days less than Aarti, we get   x = 2x – 90   By solving this equation, we get x = 90 .   Thus, 2x = 2 x 90 = 180   Part of job done by Pooja in 1 day = 1/ 90   Part of job done by Aarti in 1 day = 1/180   (Part of job done together in 1 day) = (Part of job done by Pooja in 1 day) + (Part of job done by Aarti in 1 day)   = (1/90) + (1/180)   = 3/180   =1/60   (1/60)th part of whole job will be completed by Pooja and Aarti together in one day.   Therefore, the whole job will be completed in 60 days together.   ANSWER IS 60 days
<result>C</result>
Pooja is twice as efficient as Aarti and takes 90 days less than Aarti to complete the job. Find the time in which they can finish the job together.