Group values from a custom field

Hi, I am trying to do the below in EazyBI and not sure how to do it.
There is a custom field, called area with values A,B,C,D,E,F. We can either select 1 or multiple values from that in the ticket.
The areas A,B & C belong to Platform X & the rest belongs to Platform Y.
Is there any way I can show the number of issues belonging to Platform X & Y using the custom field “area”?
Thanks