When calculating adjusted gross proceeds for the purpose of applying the tax imposed by §§ 42-7B-28 and 42-7B-28.1:
(1) Free play value provided by the operator is not included in the gross proceeds;
(2) Cash prizes deducted are adjusted to not include an amount equal to ninety percent of the free play value provided by the operator; and
(3) The federal excise tax on sports wagers imposed by 26 U.S.C. § 4401 (1982) is a deduction from the adjusted gross proceeds.