Zabbix & SNMP Memory used to Table

I’m creating a table to show remote server’s memory in used.
I have two SNMP items: ‘memAvailReal’ and ‘memTotalReal’ queried from zabbix.
I try to show memory in used with formula: MemoryInUse = 1 - (memAvailReal / memTotalReal).

How do I archieve this in Grafana?