of this amount or to apply this amount under clause (b) of sub-section (3) of this section; no amount shall be refunded to the dealer or may be applied by the dealer under clause (b) of sub-section (3) of this section unless the Commissioner is satisfied that the dealer has refunded the amount to the purchaser. (9) Where – (a) a registered dealer has sold goods to another registered dealer; and (b) the price charged for the goods expressly includes an amount of tax payable under this Act, the amount may be refunded to the seller or may be applied by the seller under clause (b) of sub-section (3) of this section and the Commissioner may reassess the buyer to deny the amount of the corresponding tax credit claimed by such buyer, whether or not the seller refunds the amount to the buyer. (10) Where a registered dealer sells goods and the price charged for the goods is expressed not to include an amount of tax payable under this Act the amount may be refunded to the seller or may be