Does anyone have a formula to calculate an APR for an adjustable rate mortgage?
for example if I have a 200,000 - 30 year mortgage that has a fixed rate of
6% for 3 years and then adjusts to a rate of 7.75 every year after that
after that, with 1500 in finance charges.

So far I can figure out the APR without adjustment of
=rate(360,PMT(6%/12,360,200000),200000-1500)*12

Any suggestions to complete the formula?