Modeling Question - Variable I/O Loan Principle Calculations

I'm having trouble wrapping my head around the "principal payment" formula for a variable loan with an I/O component.

Could anyone help me solve this spreadsheet? I have created an example problem. Not sure what would go in the "Amort" part in the highlighted Excel row.

Edit: Forgot to include the amortization timeline ... the amortization matches loan term (48 months).

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Debt Modeling_0.xlsx 34.3 KB 34.3 KB
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