Answer:
a. $600
b. 173.33%
Step-by-step explanation:
The computation is shown below:
a. For amount owed at the end of six weeks is
= The amount borrowed + interest amount
where,
The amount borrowed is $500
And, the interest is
= $100
So, the amount owed is
= $500 + $100
= $600
b. Now the APR is
Since 20% denotes for the six weeks
So, the annual percentage rate is
= 
= 173.33%