Section 9. Musical Instruments

That portion of the receipts of a music dealer which represents a trade-in of a musical instrument may be deducted from gross receipts only if the trade-in was accepted on the sale of another musical instrument of the same type as the instrument accepted for trade-in. Similarly, that portion of receipts of a music dealer which represents a trade-in of equipment for amplifying musical sound used in conjunction with musical instruments may be deducted from gross receipts only if the trade-in was accepted on the sale of other equipment for amplifying musical sound used in conjunction with musical instruments.