Ariz. Rev. Stat. § 13-3420
For purposes of determining if the threshold amount is equaled or exceeded in any single offense or combination of offenses, a percentage of each substance listed by weight in section 13-3401, or any fraction thereof to its threshold amount shall be established. The percentages shall be added to determine if the threshold amount is equaled or exceeded. If the total of the percentages established equals or exceeds one hundred per cent, the threshold amount is equaled or exceeded. If the threshold amount is equaled or exceeded because of the application of this subsection, the person shall be sentenced as if the combination of unlawful substances consisted entirely of the unlawful substance of the greatest proportionate amount. If there are equal proportionate amounts, the person shall be sentenced as if the unlawful substances consisted entirely of the unlawful substance constituting the highest class of offense.
A.R.S. § 13-3420