JavaScript Formula Help with PDF

Hello, 

I am trying to get a few calculations for a Form PDF. I don't have any experience with JavaScript, so I am hoping someone can help me! I tried to go down the Google and Forum rabbit holes to find something similar that I could adjust, but I was unsuccessful. Thank you in advance! 

1. I would like the # of paychecks to autofill depending on which option is chosen in "Role". [If "Crew Member" or "Other - Paid Weekly" then "Paychecks" = "Weeks to Repay"] or [If "Supervisor" or "Other - Paid Biweekly" then "Paychecks" = "Weeks to Repay" / 2]

2. Then I would like "Deduction/Paycheck" = "Amount Requested" / "Paychecks"