Order subtraction in a listview

Hello guys, good afternoon, again I’m here asking for help !!! It is as follows, use the Thunkable Classic and make a subtraction by request in a list, I will send an image showing how to subtract, being: the second value - the first, and the third value - the second, could someone help me With any solution, blocks you want to use to perform this action? Thanks !!
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I replied this privately. You may decide to copy/paste the block here so that the forum question appears complete.

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