Cheryl receives a sixty-year annuity-due. The annual payments are $3,000 during the first twenty years and $6,000 during the next forty years. David receives a perpetuity-immediate with annual payments. The odd numbered payments are P and the even numbered payments are 2P. The present value of Cheryl's annuity and David's perpetuity are equal if they are calculated using i=5%. Find P.