Need help with subtraction formula using Javascript

[Kristin25692044x8kt]

I am trying to fill out how many weeks someone works. 

In the first question, I'm asking how many weeks off work someone takes (WeeksOff)

I would like (WeeksWorked) to automatically calculate, 

so it should be 52 - WeeksOff

Can someone help me create a script?

[ls_rbls]

If each of the fields are just blank fields in which a user will type in a number value, why not use Simplified Field Notation?