can you please answer these questions and explain it? thank you!

1. B, interested in a particular car at a car exchange company, asked 5 for the price. 5 said: \"P3500300.\" B however could not make up his mind whether to buy or not. So 5 told B, \"B, I'll give you a week to make up your mind. In the meantime, I will reserve this car for you.\" Before the week is over, can 5 withdraw the offer to sell the car for P3,500,000? 2. A offered to sell his house and lot for P10M to B, who was interested in buying the same. In his letter to B, A stated that he was giving B a period of one month within which to raise the amount, and that as soon as B is ready, they will sign the deed of sale. One week before the expiration of the one-month period, A went to B, and told him that he is no longer willing to sell the property unless the price is increased to PISM. May B compel A to accept the P10M rst offered, and execute the sale? Reasons 3. X, desiring to buy certain property, hired an expert to ascertain its true value. But the expert's opinion turned out to be wrong and X was, therefore misled. May X ask for the annulment of the contract? 4. A and B entered into a contract with X. A's consent was obtained only because B had deceived or defrauded him. May A ask for annulment of the contract with X? 5. If a particular piano is sold for P500,000 what is the object and what is the cause