@lastTimeUseTT another method that is probably close to what @ThomasM125 suggested but will be technically exact:
$161,000 * interest rate * number of days the mortgage was outstanding in 2019 / 365.
The loan would have amortized (slightly) over the course of the year, but the assumption is the part of the loan that was NOT 'acquisition debt' would paydown first while the $161,000 of acquisition debt doesn't
