Use "Numbers" field between Ticket & Organization in order to Substract a result

Hello Zendesk community,

I hope you are all doing well,

I searched for articles referring to this kind of need but was unable to, so I come here hoping anyone has an idea.

We have a "Number" field on Organization, that we will call "Available Vouchers"

I'm planning to set a Field on ticket, editable by agents, the name will be "Vouchers used".

I would like to know if this is possible (and how) to automatically have this behaviour :

- Whenever an agent fills the "Vouchers Used", we would like the number set up in it to be automatically reduced from the "Available Vouchers" field.

Example : 

- Organization ABC, "Available Vouchers" is equal to 10

- Ticket #12345 linked to Org ABC, my agent fills "Vouchers Used" to 3

--> I would like the Available Vouchers field to be automatically changed to 7 (10 - 3).

Is there anything I can do which would allow me to do such kind a thing ?

My main objective is to be able to pilot the number of vouchers used among tickets.
I know I could do it with "Explore", but maybe we could do it at an upper lever ?

Thanks in advance for your help everyone,

Have a great day !

Regards,