Bronn takes out a fully amortizing, $5/1$ hybrid, adjustable rate mortgage of $$161599\mathrm{.}21$ with $18-$year maturity.

The interest rate is indexed to SOFR and the margin is $3\%.$

At the time of the loan origination, SOFR is $1\%$; it is expected that SOFR will be $3\%$ at the end of the $5$th year.

Bronn$$s monthly payment during the $3$rd year of the mortgage equals $$\_\_\_\_$ per month.