9514 1404 393
Answer:
659
Explanation:
We assume the daily rate increases at each multiple of $50. When the balance reaches $50 on day 25, the pay on day 26 is $2.25.
Similarly, when the balance reaches 9628.75 on day 658, the pay will be $50 on day 659.
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I found this easiest to solve using a computer program. A spreadsheet can do it by computing the number of days between raises. This is shown in the attachment.