how do I resolve kernel_task activity

Has the user tried the link in Top Left of this webpage ?

Incase it was over looked

 If kernel_task is using a large percentage of your Mac CPU

Dust in the fan? A user on Stack Exchange had the same problem:

https://apple.stackexchange.com/questions/325716/kernel-task-writes-huge-amounts-of-data-to-disk-1tb-how-to-diagnose

iFixit may have a guide for this.

Use the Activity Monitor application and make sure to use View >> View All Processes 

What process or processes are using the Most CPU  and Memory.

Often times - the issue maybe not a single Process  alone but a combination of Processes

Also, when the computer is using so much Memory - it can be a indicator of a Lack Of Empty Spaces on the Drive.

In which case, the CPU and Memory usage would become Much More because it is searching for Empty Space to save all the Changes the user is performing.

Also, depending on the number of  Open Tabs in your Browser, they can also affect Memory Usage.