Get last row

[Soporte_Gestion]

Hello!
I need to compare the last value row with the new added row, for the same item.
Eg: Last row that been added was a row with 10 bananas, now I add a row with 5 bananas, and I need to check the difference between those rows 10 bananas - 5 bananas = 5 bananas.
How can I do it?