Changing Inventory number Column in Different Board when Status Changes in Another Board

Hello,

Sorry if I’m in the wrong board. I’ve only found confusing answers to my questions elsewhere.

I’m making cookies and on Board 1 of the process of cooking making (Design, Bake, Pack).
On another Board 2 have inventory management with flour, sugar, butter. Each of these items has a number column showing the starting amount (1,000g).

What I want to do is when Board 1 status of Bake changes to Done, I want the flour in Board 2 to decrease by 100g.

I’ve tried mirroring but I don’t think I’m doing it properly.

Any way to achieve this?

Thanks