AN ACT relating to taxes on retail sales; providing for the submission to the voters of the question of whether the Sales and Use Tax Act of 1955 should be amended to exempt from the taxes the amount of any allowance against the selling price given by a retailer for the value of a used portable electronic taken in trade on the purchase of another portable electronic under certain circumstances; providing for the same exemption from certain analogous taxes if the voters approve this amendment to the Sales and Use Tax Act of 1955; and providing other matters properly relating thereto.