Lee Company of Westbrook, Connecticut, manufactures pressure relief inserts for thermal relief and low-flow hydraulic pressure relief applications where zero leakage is required. A machine purchased 3 years ago has been book-depreciated by the straight line method using a 5-year useful life. If the book value at the end of year 3 is $30,000 and the company assumed that the machine would be worthless at the end of its 5-year useful life,

(a) What is the book depreciation charge each year?

(b) What was the first cost of the machine?