Math conditions for Elasticsearch Terms


I want to create an alert:
If the query value is more than customer_limit by 50% it fires.
It should look like this:
$A > ${customer_limit} * 1.5

In the Custom annotation name it works in the following way:
{{ $values.A.Labels.customer_limit}}
But I don’t understand how to specify it in the Math field

Could you please advise on how to describe that in Math Conditions?
I’ll be appreciative of any advice.