The salvage value S (in dollars) of a company limosine after t years is estimated to be given by the formula below. Use the formula to answer the questions.
S(t)=500,000(0.8)t
What is the rate of depreciation (in dollars per year) after 1 year?
What is the rate of depreciation (in dollars per year) after 10 years?
What is the rate of depreciation (in dollars per year) after 15 years?