CAN YOU HELP ME WITH THIS ONE.

PLEASE REFER TO ARTICLE 1590 OF THE CIVIL CODE (PHILIPPINE LAW)

1. Simon sold and delivered to Brian a parcel of land for 2 million pesos payable within 30 days from the date of the contract. Soon after the sale, Xavier claims ownership over the land by virtue of a prescriptive title. May Brian suspend the payment of price? Why?
2. If, in order to avoid trouble, Brian pace of Xavier to settle latter's claim to the land, may Brian recover the amount paid as against Simon upon Simon's warranty in case of a vacation? Reason.