Grafana alert for cpu/memory usage

Hi, I’m new on Grafana and I work on v8.5.0. I want to make an alert through Grafana that define if the CPU or Memory usage above threshold (let say 85%) it will firing an alert. What I have now are time series limit CPU/memory

limit query:
kube_pod_container_resource_limits{namespace="$namespace", pod="$pod", resource="cpu"}

and cpu/memory usage query:
sum(rate(container_cpu_usage_seconds_total{namespace="$namespace", pod="$pod", container!="POD", container!="", pod!=""}[1m]))

Logical to make the percentage is, (resource_usage_query)/(resource_limit_query)*100 . I’ve tried to combine both query same as the formula but ended with nodata value. Is there any syntax or something I missed? I appreciate any suggestion.