Andrea plans to make 20 annual deposits at the end of each years of $100 each into a fund in order to accumulate a target amount of K on the date of the last deposit. The fund earn 6.2% effective per annum.

Andrea makes the first 5 deposits of $100 However, the fund earns only 1.5% effective up to this point. Andrea determines that she would have to increase the amount of the last 15 deposits to X in order to accumulate to the original target of K, assuming that the fund continues to earn only 1.5% effective.

Determine X.