How to subtract two fields from two seperate portals

[MattPrice]

hi, fairly new to filemaker

i have two portals each with various different fields inside but there are two fields i need to subtract which are "Qty Sold" and "Qty".

both of these portals show records relating from the same table but i am unsure on how to calculate this function

 

[Lee Smith]

Hi Matt and welcome to the FMForums,

Assuming that the two fields are in the same table, just create a new Calculation field

Qty - Qty Sold

Lee