Answer: Sunk cost
Step-by-step explanation:
Sunk cost also sometimes referred to as past cost is a cost that has already been spent by an individual or firm and cannot be recovered.
From the question, if $500 was spent last week in fixing the transmission in a car and the brakes are now acting up, and one has to decide qwhether to fix them or trade the car in for a newer model.
The amount spent on the brake situation in this case is a sunk cost as it has already been incurred and nothing can be done about it anymore.