buy & sales data

[maeleoin]

Have a list or trades, buy and sell data. Want to subtract purchase amount from sales amount.
How can I change purchase to negative so that I can use subtotal to sort transactions for different products?

Sample

product Amount Gain/loss (Other fields like date and quantity not to be subtotaled)
buy abc $5
sell abc $6
sell ayz $3
buy ayz $1
buy ayz $ 2.5

I am a novice at Excel and realize this problem should have been solved many times in the past.

 

[baitmaster]

welcome to the board

use =SUM(amount range) to add up all the values in a range of values. Use =SUMIF(amount range,">0",amount range) to add only those values that are positive. Use =SUMIFS(amount range, amount range,">0",product range,"abc") to add up only those values that are positive and relate to abc