SMAlvarez wrote:
Ok so the "the monthly payment" is 30*12*PMT(.06/12,30*12,255000)?
and "the total amount paid in 30 years" is $300,000?
and "total interest paid" - whatever 300,000 - 255,000 is?
Is that true?

No.

SMAlvarez wrote later:
maybe im wrong. Is the monthly payment whatever the answer is to
PMT(.06/12,30*12,255000)

Yes, with the caveats that I mentioned in an earlier posting. The
monthly payment is probably either PMT(6%/12,30*12,255000) or
PMT(RATE(12,0,-1,1+6%),30*12,255000), depending on what your teacher
meant by "6% APR". I suspect your teacher did mean "6% annual interest
rate". In that case, your formula is correct. (Note that .06/12 is
the same as 6%/12.)

I had said that 30*12*PMT(...) is the total amount paid in 30 years.
That is very much more than $300,000. Enter the formula
=30*12*PMT(...) into a cell and see the result.

And I said that the "total interest paid" is the "total amount paid"
minus the principal ($255,000). That is =30*12*PMT(...)-255000.