Answer:$40,000
Step-by-step explanation:
The $40,000 represents cost of the asset on purchase which is a sunk cost thereby no longer relevant to decision making because it has already been incurred and there is nothing that can be done to recover the cost.
$31 000 which is what is to be received by trading his spotter truck is still relevant because it can be earned, the $25,000 to be saved in cost is also relevant to determine cost reduction and same implies to the current sales price of $120,000 which is the fund to be provided in buying a new truck..