Please answer it correctly​

If f(x)=3x+1 and f^-1=x-1/3, then f^-1(7)=

Ricky takes out a $31,800 student loan to pay his expenses while he is in college. after graduation, he will begin making payments of $190.66 per month for the next 30 years to pay off the loan. how much more will ricky end up paying for the loan than the original value of $31,800? ricky will end up paying $ more than he borrowed to pay off the loan.

What is the average diastolic blood pressure for adults