Calculate a percentage based on two cloudwatch metrics

I am running Grafana 9.1 and would like to calculate the percentage of used inodes on an EC2 instance.

I have configured the Cloudwatch agent to send disk_inodes_used and disk_inodes_total, as it doesn’t have the option for percent used as it does for disk usage.
With these two numbers, I was hoping to calculate the percent of used inodes, but I’m not sure how to achieve that if it is even possible.

Any tips would be greatly appreciated.
Thanks in advance