Sophia's purchases are increasing each month by 25%. In September, the purchases were $32000. In October, the purchases will be $40,000. In November, the purchases will be $50,000 which is 25% more than the October purchases of $40,000. Sophia pays 50% for the November purchases in December (the month after) and 50% in January (2 month after sale), so she will pay $25,000 in December and $25,000 in January for purchases in November.