In 20x1, G Co. started to develop a patent. Total costs incurred during the year amounting to P400,000. On January 1, 20x2, the patent was fully developed. Legal and registration cost incurred in registering the patent amounted to P300,000. It was estimated that the patent has a useful life of 25 years. In 20x4, G Co. started to develop a new improved patent to extend the life of the old patent. Development costs totaled P800,000. On January 1, 20x5, the new patent was completed and legal and registration costs incurred to register the new patent amounted to P320,000. It was estimated that the new patent will extend the life of the old patent by another 20 years starting January 1, 20x5. How much is the amortisation expense in 20x5?