Lukaz entered into an agreement with Mamfee wherein Mamfee will deliver a certain thing to Lukaz who gave Php150,000.00 in payment thereof. However, if Mamfee fails to give the thing on the agreed date, she will give a tin of opium to Lukaz. Supposed on the agreed date Mamfee failed to deliver the thing promised, (a) Can Lukaz demand the delivery of the tin of opium as penalty? (b) What is the remedy of Lukaz?