hello i came here cuz my problem seems somewhat complex, it may require something like a macro or VBA anyway here goes nothing lol
and im sorry for my lack of explanation im new to excel. but ill try my best

i want a cell to perform this following operation listed under.

ok, = whatever number i put in the cell, it will look at the number and subtract from another cell

another example is, whatever number i put in cell A2 lets say 3,it will subtract 3 out of whatever number is available in A1,

also in other words, say we have 10 in cell A1, if i add 3 in cell A2, cell A1 will automatically turn to 7.
and if theres the adding version for this it would be great!

if anyone knows how this could be done, it will be much appreciated.