frank hired sam to act as frank's sales agent in his jewelry store. frank gave sam actual express authority to sell items of jewelry up to $1,000 without checking with frank; however, if the price was over $1,000 sam was to check with frank before making a sale. one day a customer wanted to buy a necklace for $1,500 and sam sold it to her without first checking with frank. when frank learned of this, he was upset because the price was a mistake; it should have been $3,000. frank wants the customer to return the necklace. is the customer required to return the necklace in this case?