Bob wants to purchase a perpetuity that pays $100 per year with the first payment due at the end of year 11. He can purchase it by either of the following plans: (i) Pay $90 per year at the end of each year for 10 years or (ii) Pay $K per year at the end of each year for the first 5 years and nothing for the remaining years. Find K.

Answer: K= 151.94, but I'm not sure how to get there