Help to find last balance of account for person

Hi All,

I have a large data set which contains prices of a product and the volume (unit held) for each date. However, I am looking to change the price of units, which in turn would change the volume of units transacted. The dataset contains multiple buyers, products and dates. So if I change the price, in turn the units transacted would change and therefore the closing balance. Is there an easy way to find this new/adjusted balance for that person and product?

If someone places an order for $1,000 and price is $100, have 10 units. Then if I change price to $50, they would now have 20 units in that product. However the spreadsheet contains multiple products, and am unsure of the last date they traded to find their current balance when it comes to newer transactions.

Can anyone please assist with a formula which can find their last balance of units?

Greatly appreciate any assistance.

Kind regards,

Callum