A portfolio has a Macaulay duration of 15.8368 years and have the following assets all yielding at an annual effective rate of 5%:

(a) one 10-year annuity immediate with level payment X;

(b) one perpetuity immediate with level payment 0.8X;

(c) one 30-year $1,000 par value bond with annual coupon rate of 5%. Calculate X.