Sarah bought stock on margin 8 months ago borrowing $10,000 at 7% EAR. She has just received a margin call for $3000 and her maintenance and initial margin was 15%. What must be the current value of the assets, BEFORE THE CALL, in her margin account? [Choose closest]

a) Cannot be determined with the information provided, we need the number of shares

b) Cannot be determined with the information provided, we need to know the original asset value

c) $0

d) $9,310.51

e) $12,310.51

The answer is d) but why?