Simple intrest
posted by Scott .
Bill Moore is buying a van. His April Monthly intrest at 12% was $125.00 What was Bills principal balance at the beginning of April Uese 360 days

0.12 interest per 360 days =
0.12 x (30/360) for April which has 30 days.
Then 0.12*loanamt x (30/360)= 125
solve for loanamt. I get 12,500.
Check my thinking. 
Shawn Bixby borrowed 17000.00 on a 120 day, 12% note. After 65 days, Shawn paid 2000.00 on the note. On day 89 Shawn paid an additional 4000.00 What is the final balance due? Determine total intrest and ending balance due by the U.S. Rule. Use ordinary intrest