find out the tax base for the Oklahoma state sales tax and classify the tax as progressive or regressive.

How could the tax base for the Oklahoma state sales tax be narrowed? In answering this problem, address only the sales tax...NOT income, property or other taxes.

Assume the tag fee charged every year for every vehicle new or old, is a fixed amount of $100. Would such a tax be classified as progressive or regressive, and why? describe. Hint: The tax is not proportional.