Investment Selection With Cell Selection

I'm trying to build an investment calculator. Tried searching "calculator" as keyword but return nothing similiar.

There are eight cell : [ A ][ B ][ C ][ D ][ E ][ F ][ G ][h]

[ H ] is price of the leverage

[A] is X balance
[b] is X lot size
[C] is X amount of money use to get x lot
[D] is X percentage of money use to get x lot
[E] is X point gain
[f] is X money gain
[G] is balance + money gain

Ignore the formulae for leverage to determine 1 lot price. Take 1 lot = 250.

What I'm looking for is when I enter any value at cell B, C or D, it will automatically calculate the value for either B, C or D cell.

Let say, the balance is 10000.

If I enter 2 at cell B. Then, it will calculate the value for cell C & D.

If I enter 750 at cell C, then it will calculate value for cell B & D.

If I enter 25 at cell D, it will calculate value for cell B & C.

how to use OR Selection in excel.