11. Obligation to state price separately on composite offer. Where a dealer or producer makes an offer to enter into a transaction for a consideration to be given as a whole in respect both of a sale of any drug and of some other matter, the dealer or producer making the offer shall state in writing the price which he assigns to that drug, if he is required to do so by any person to whom the offer is made, and the offer shall be deemed for the purposes of this Act to be an offer to sell that drug at the price so stated.