Final answer:
The straight line depreciation equation for the car is determined by subtracting the residual value from the initial value and dividing by the useful life in years. The value of the car after w months can be found by converting w months into years and using the depreciation equation to calculate the decreased value.
Step-by-step explanation:
To write the straight line depreciation equation for the car, we can use the formula:
Depreciation per year = Initial value - Residual value / Useful life in years
Using the given information, the initial value is $18,495 and the car depreciates to zero after 9 years. So, the equation becomes:
Depreciation per year = $18,495 - 0 / 9 = $2,055
To find the value of the car after w months, we need to convert w months into years by dividing w by 12. Then, we can use the formula:
Value of the car = Initial value - Depreciation per year * Number of years
Substituting the values, the expression becomes:
Value of the car after w months = $18,495 - $2,055 * (w/12) dollars