[Rounder]

Hi,
New to the forum as I am looking for an answer on using one field to change another. Not the sharpest tool in the shed so would appreciate any help.
I have created a merge document to send to tenants when it is time to renew their lease. If they don't renew the lease they go to a month-to-month payment at an increased rent of $20.00 more per month. I have inserted a field to show the current rent, say $500.00. How do I make a second field to show that the rent will increase to $520.00 if they don't renew the lease and go to a month-to-month payment schedule?

Thanks for any help available.