I want Latest day minus previous day

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I extracted data from excel file.

 use code

of the date 01/02/2023

of the date 01/03/2023

I want Stroke_Day = Stroke_real_time on 01/03/2023 minus Stroke_real_time on 01/02/2023.

 I want Stroke_Day = Stroke_real_time Latest day minus previous day