Please answer the given questions and show the solutions completely. Please do me a favor to answer both of these questions. Thank you very much!!

1.) A machine costs P8,000 and an estimated life of 10 years. If its book value at the end of 8 years is P2,000, determine its salvage value using straight-line method. 2.) A device was purchased that amounts to P25,000 including tax and other fees. The book value of this device in the 5th year and at the end of its useful life is P15,977.3876 and P5,000, respectively. Determine the number of useful life of the device if interest is at 4%