Leticia purchased a home on July 1, 2020, for $200,000. She paid $180,000 down and financed the remaining $20,000. On January 1, 2022, when the outstanding balance of her mortgage was $15,000 and her home was valued at $300,000, Leticia refinanced her home for $200,000. With the $200,000 loan, she paid off the remaining $15,000 balance of her original mortgage, she used $35,000 to substantially improve her home, and she used the remaining $150,000 for purposes unrelated to her home. During 2024, Leticia made interest-only payments of $15,000 on the loan. What amount of the $15,000 interest expense is Leticia allowed to deduct in year 2024?