Please show formulas i need to know and understand how values are obtained, thank you will rate if complete formula

pinoybix.org b. P30,420 C. P40,oo0 d.P30,0o0 1205. An engineering firm from purchased, 12 years ago, a heavy planner for P50,0oo with no salvage value. As the life of the planner was 20 years, a straight Line depreciation reserve has been provided on that basis. Now the firm wishes to replace the old planner with a new one possessing several advantages. It can sell the old planner for P10,000. The new one will cost P100,000. How much new capital will be required to make the purchase? -a. P60,000 b. P55.ooo -C. P66,000 d. P57,ooo