The purchase price of an instrument is $12,000 and its estimated maintenance costs are $500 for the first year, $1500 for the second and $2500 for the third year. After three years of use the instrument is replaced; it has no salvage value. Compute the present equivalent cost of the instrument using 10% interest.

a) $14,070                 

b) $15,570                        

c) $15,730                       

d) $16,500