If I am paying 17.9 annual percentage rate on one cedit card and paying 8.9 annual percentage rate on a second credit am I paying 26.8 monthly?

No.
You are paying 17.9% yearly on one card and 8.9% yearly on the other.
You can't figure out a total % rate, at least not easily. It depends on how much you charged and when.
If someone owes 2,000 at 9% and 200 at 18%, most of it's on the lower rate, bringing the % down overall, right?
Don't forget that interest snowballs rapidly and you ARE CHARGED ON NEW CHARGES JUST BECAUSE YOU HAVE OLD ONES.

You might want to look into transferring debt on the higher one to the lower one.