To find the loan amount after 9 years using the given equation of the line of best fit \( y = 15,413 - 1,635x \), we need to substitute \( x = 9 \) into the equation.
\[ y = 15,413 - 1,635(9) \]
Calculating \( 1,635 \times 9 \):
\[ 1,635 \times 9 = 14,715 \]
Now, substitute this back into the equation:
\[ y = 15,413 - 14,715 \]
\[ y = 698 \]
So, the loan amount left after 9 years is \( \text{$698} \).