An n-year zero coupon bond with a par value of $1000 was purchased for $600. A 2n-year $1000 par value bond with annual coupons of $x was purchased for $850. A 3n-year $1000 par value bond with annual coupons of $x was purchased for $P. All three bonds have the same yield rate. Compute P. (ANSWER: $816.25)