Suppose Hassan decides to explore the costs of financing a more expensive vehicle. The

more expensive vehicle costs $$34,900$ in total and qualifies for the $3\mathrm{.}9\%$ dealer financing for

$48$ months or $$2500$ cash back. What is the highest effective annual rate of interest at

which Hassan should borrow from the bank instead of using the dealer's $3\mathrm{.}9\%$ financing?