An engineering firm purchased 25 years ago a mini power plant for Php 5.0 M. Other expenses including repairs amounted to Php 500,000. The mini power plant is up to next 25 years only and for the plant to operate. The salvage value is Php 500,000. Determine the depreciation charge during the 22nd and 42nd year. Also determine the book value at the end of 25th and 45th years if interest is 12% using

a) Sum of the Years Digit method

b) Sinking Fund method

c) Double Declining Balance method.