Hi

I am trying to dynamically link three cells (A1, A2, A3), where the third cell (A3)is the sum of cells(A1, A2) - totalling 100%. I need a formula which will automatically adjust A1 if A2 and vice versa and keep A3 fixed to 100%.

I am new to writing formulas in Excel and any help with this will be greatly appreciated. I've been going round and round this with no progress.