There shall be excepted and deducted from the total gross income upon which the tax levied herein is computed so much thereof as is derived from transactions in interstate or foreign commerce, any payment collected by a public utility business which directly represents a tax levied by the United States, the state of Washington, or the city of Lacey pursuant to this chapter, and amounts derived from business which the city is prohibited from taxing under the constitution of this state or the Constitution or laws of the United States. (Ord. 749 §1 (part), 1985).