Getting cells to reflect/mirror changes made in another cell.

[MrSuperConfused]

Cells: B2, C2, and D2 are the cells.
Values: 19, 7, and 12.
If I add 1 to 19 and make it 20. I need 12 to change to 13.
If I add 1 to 7 and make it 8. I need 12 to become 11.

Possible? How?

 

[Peter_SSs]

In D2, put the formula
=B2-C2

 

[MrSuperConfused]

Well now I feel super dumb

 

[Peter_SSs]

Well now I feel super dumb

No need to. The forum often helps to remove 'brain blockages'.