Final answer:
Buying the car and selling it after three years would cost $15,000.
Step-by-step explanation:
To determine whether it is more cost-effective to buy or lease a car, we need to compare the total costs of each option.
If you buy the car for $18,000 and sell it after three years at the residual value of $12,000, your total cost would be $18,000 - $12,000 = $6,000.
On the other hand, if you lease the car, you would make a down payment of $3,000 and have monthly payments of $150 for three years, totaling $3,000 + ($150 * 36) = $8,400.
Therefore, buying the car would cost $6,000, while leasing it would cost $8,400. Since buying the car is less expensive, the answer is d) Buying the car and selling it after three years would cost $15,000.