At simple interest it will be 939+939×6×0.08=$1389.72.
A translation
(I'm assuming that this isn't multiple choice since you didn't include the answer choices.)
Pair of shorts costs $12. Shirt costs $48.
Difference between the two is $36.
Forts then you take the 1-6 to get the money back and get your credit
The answer is 4/6 which can be reduced to 2/3.