Answer:
The constant of proportionality in the inverse variation is -3000
Explanation:
Given that the initial value of the car was X, after owning the car for 3 years the value is $15,000 and the value after 5 years was $9,000 we have;
At year 3, value of car = $15,000
At year 5, value of car = $9,000
Rate of change of car value with time = Constant of proportionality
Rate of change of car value with time = (15000 - 9000)/(3 - 5) = -3000
The constant of proportionality = -3000
Therefore;
y - 15000 = -3000 × (x - 3)
y = -3000x + 9000 + 15000 = -3000·x + 24000
The value of the car, y with time,x is, y = -3000·x + 24000