Explanation

1% of $450 is $4.50, so 0.5% is $2.25. That’s the amount Raymond pays back every week.

Because he has paid back $18 in total, divide 18 by 2.25 to determine the total number of payments:
\(\frac{18}{2.25}= 8.\)


So Raymond has made 8 payments, once every 7 days. The payments themselves spread over only a 7-week period (in the same way that 2 payments spread over only a 1-week period).

Raymond waited 1 week to begin repayment, however, so a total of 8 weeks, or 56 days, have passed since he borrowed the money.