Workflow to adjust field

I’m working on a basic inventory system. I have created a form/page to make inventory adjustments. I’m now working on a workflow that triggers when a new record is added to my inventory adjustment table (which i’m using to log the adjustments). I have the workflow setup now and it pulls the quantity change field from the adjustment table but instead of adjusting the quantity on hand amount (located in a separate table) it just changes the value to whatever the quantity change field is set to.

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I’m unsure how to configure it so that the quantity on hand is changed by the value of the quantity change. I’ve tried typing in formulas provide through AI but have had no luck. Any advice?

Found a solution that was posted in the forums a while back. Essentially I needed to create a field to calculate the changed quantity + on hand quantity and have the workflow use that calculation when adjusting the data table. The field I created will always have its value changing but the actual on hand quantity is only adjusted when it runs which is when a new entry is created.