Automatically assign priority based on values selected in various list boxes?

Automatically assign priority based on values selected in various list boxes?

Hello, I'm brand new to Zoho Support and trying to set it up for a support center.  I need to assign a priority code based on multiple factors.  For example:

If Impact on A = High then assign value of 3
If Impact on B = Med then assign value of 2
If Impact on C = High then assign value of 3
If Impact on D = Low then assign value of 1

Add all values, in this case 3+2+3+1=9 to get Impact score.

If Impact score >=7 & <= 9 then Priority should be set to Medium (such as this example).

Could you please let me know the best way to approach this?  Thank you.