Answer: $70 value for the belt.
Explanation:
Opportunity cost is the benefit that is foregone for an individual by choosing one alternative over other alternatives available to him.
If the opportunity cost is lower for an individual then this will benefit him whereas if the opportunity cost is higher then this will not benefit the individuals.
Therefore, the opportunity cost of the helicopter was $70 for the belt. It is the highest opportunity cost that was incurred by deciding to purchase the helicopter.