A manufacturer offers an inventor the choice of two contracts for the exclusive right to manufacture and market the inventors patented design. Plan 1 calls for an immediate single payment of $213857. Plan 2 calls for an annual payment of $17635 plus a royalty of $1.68 for each unit sold. The remaining life of the patent is 10 years. MARR is 8% per year. How many units must be sold each year to make Plan 1 and Plan 2 equally attractive?