You are given: i. The present value of an annuity-due that pays 300 every 6 months during the first 15 years and 200 every evey 6 months during the second 15 years is 6000; ii. the present value of a 15-year deferred annuity-due that pays 350 every 6 months for 15 years is 4000; and iii. the present value of an annuity-due that pays 100 every 6 months during the first 15 years and 200 every 6 months during the next 15 years is X. Determine X