Halcrow, Inc., expects to replace a downtime tracking system currently installed on CNC machines. The challenger system has a first cost of $70,000, an estimated annual operating cost of $20,000, a maximum useful life of 5 years, and a $10,000 salvage value anytime it is replaced. At an interest rate of 10% per year, determine its economic service life and corresponding AW value. Work this problem using a hand calculator.

A) Economic service life is 5 years

B) Economic service life is 4 years

C) Economic service life is 3 years

D) Economic service life is 1 year