wrongdongdirection,
Welcome to the forum. 
If this is an internship assignment or homework question we try avoid assisting with those as the first port of call should be your tutor, supervisor or teacher.
In any other case - as we do not like to deliver ready to use code or solutions on request - you may start reading the help you can find in the internet.
Such as …
https://4sysops.com/archives/do-the-math-with-powershell/
You should always read the complete help imcluding the examples to learn how to use the commands.
If you have started trying and just got stuck with your code you should share it here (formatted as code How to format code on PowerShell.org forum ) and we will try to solve your issues together with you.