To pay for an $$18,600$ fishing boat, Frank made a down payment of $$4300$ and took out a loan for the rest. On the loan, he paid monthly payments of

$$256\mathrm{.}96$ for $5$ years.

$($a$)$ What was the total amount Frank ended up paying for the fishing boat

$($including the down payment and monthly payments$)?$

$$$

$($b$)$ How much interest did Frank pay on the loan?

$$$