Amount of coupons used

Summary:

Amount of coupons available to use

Content (required):

When we do a promotion we inform the amount of coupons that will be used.

My question is how to identify the still available quantity of coupons to use?

(Total coupons - used coupons) = ??

Version (include the version you are using, if applicable):

23.08

Code Snippet (add any code snippets that support your topic, if applicable):