Credit card has slightly lower interest rate.
Let's take a look at both interest rates for 1 year and see what costs more. First, the credit card at 17% apr compounded monthly.
Each month, 17%/12 interest will be taken. The total interest over the year will be
(1 + 0.17/12)^12 = 1.183891728 times the original debt.
Now let's look at the loan from the parents. Over 1 year, you'll be accumulating 2 interest payments. The formula for the year will be
(1 + 0.09)^2 = 1.1881
Comparing the overall rate between the credit card and the parents, the credit card is slightly lower than the parents.
