Tom took out a fully amortizing, $7/1$ hybrid, ARM of $$300,000$ with $15-$year maturity.

The interest rate is indexed to SOFR and the margin is $1\%.$

At the time of the loan origination, SOFR was $2\%.$

At the end of the $7$th year, the SOFR was $5\%.$

For the $90$th month, Tom$$s monthly payment equals