I am a business owner in CA and it is time to calculate the taxes owed to Board of Equalization. My gross sales are $124,000 with a total of $86,000 in non-taxable sales. The current tax rate is 8.25%, what is the amount of taxes that I owe to the Board of Equalization?

Pretty basic math. Gross -nontaxable =taxable X %. You can do that!

Yes, it is so basic that I doubt the OP is actually a business owner, but rather a student looking for help with a homework problem.