A major airline purchases a particular type of plane for for $75 million . The company estimates that the salvage(resale) value of the plane is estimated well by the function

S=f(x)=72-0.0006x

where S equals the salvage value(in million of dollars) and x equals the number of hours of flight time for the plane.

(a). What is the salvage value expected to equal after 10,000 hours of flight time?

(b). how many hours would the plane have to be flown for the salvage value to equal zero?

(c). What interpretation would you give the y-intercept? Why do you think this does not equal 75?