how to enter calculations between variables

Hello everyone. I developed an application for personal billing organization. But now I'm facing a problem ... I need to SUM selected invoices, where I get the total amount back in one field, then I need to enter the amount paid to finally return the difference value in another field.


before we start giving suggestions...

What is the exact problem?

What are your initial thought how to approach this?

Give us an initial approach how you think you should tackle this.

good luck!


hi J.

thanks for your reply.

I already solved my problem :)
i'm a low coder but i'm very stubborn so i find a way for my needs.

Congrats for this great platform, I'm really enjoying outsystems.

Best regards


Isn't that mandatory for being a developer? :)

Even though you answered your own question, which is great, but how did you solve it ;)

It seems he did a sum in an aggregate J