3000 loan, with payback minimum 100 points a week, starting December 10th, 2017.
Minimum interest charged is 300 points (if 3000+300 is paid back in less than 13 weeks, before March 11th, 2017). Maximum interest charged is 1200 points (if 3000+1200 is paid 21+ weeks later, after May 6th, 2017).
Add 20 points for each week where 100 points payment is late or absent.