Here you go. The answer is r = c/ pi. Simply divide both side by pi, in order to isolate the variable r.
I can see 3 main groups:
The poor - they have a promise of a “reward” in heaven if they obey Church and King.
The Church and King - it provided them with great temporal power. Ever hear of the Divine Right of Kings?
Those people that Xtian armies or “missionaries” held at sword point and gave them the choice of convert or die.
I thnk it is age hope it helps