Tracking Next Call Due Date IF Relationship Type is Current Client?

I'm really new at using calculated fields, so I am hoping someone with a little more knowledge can assist me on this.

The following article walks you through creating a Next Call Due Date based on the size of the account (small, medium, and large). http://support.sugarcrm.com/Knowledge_Base/Studio_and_Module_Builder/Sugar_Logic/Sugar_Logic_Walkthrough_Next_Call_Due_D… 

I'm trying to create a similar field.

I would like the "Next Call Due Date" to be set for 30 days if the contact relationship type equals current client. I imagine that the formula has to be simple, but all the different variations I've tried do not work. 

Have anyone else created a calculated field like this- or are you aware of any documentation I may have overlooked?

Also, I'd be curious to read up on how to become more familiar with calculated fields. I feel like I could really open some doors if I gain some knowledge on this topic.


Thank you!!!