Answer:
$8.55
Step-by-step explanation:
Differential cost is the difference between the two alternatives cost of production.
The management may decide to improve the features and quality of a particular product so as to sell it at a higher price and earn more revenue.
The additional cost incurred to arrive at this new feature , also known as the incremental cost is the differential cost
In the scenario given , the additional cost is $8.55 as stated.