First, calculate the total money of the payments for 36 months, for both cases, with credit card company or not.
Proceed as follow:
With credit card:
$186 x 36 = $6,696
Without credit card:
$162 x 36 = $5,832
next, subtract the previous results:
$6,696 - $5,832 = $864
Hence, Janine will save $864 if she borrow the money from bank and pays off her credit card