Suppose you take a $3/1$ interest$-$only, $30-$year ARM for $$180,000\mathrm{.}00$ with an interest$-$only contract rate of $3\%$ and a following rate of $7\mathrm{.}75\%$ in year four. Assume you pay $1\mathrm{.}5$ discount points.

What would be the effective cost if the loan is repaid at the end of year $4?$