This really is left up to you as long as you have an odd number in the tens place and a 7 in the ones place. How big (or small) the number is is up to you. As long as it is at least 17, it's pretty much up to you.
Answer:
ye has bad. he nf nv nnfcnxb xx. b DC x b x dnf znfbe xngrh cngbf
Your answer would be
-7-(-i)+6-3i
You would get 2015.17568 as the interest rate i believe