Answer:
$70
Step-by-step explanation:
The opportunity cost is the value in which the advantage is produced from the options available. The best gain is term as the opportunity cost
In the question, it is given that the offered price is $70 and the yesterday price is $30 which was paid which terms as a sunk cost. This cost is not useful for decision making as well as for computing the opportunity cost also
So, only $70 would be considered