Final answer:
Without knowing the exact amount of data Denny used over his individual allowance, we cannot calculate the extra cost he owes. The family exceeded their data plan by 4.6 GB, but this does not specify Denny's usage. Therefore, it's not possible to determine what Denny owes with the information given.
Step-by-step explanation:
The Halloran family's cell phone plan allows for 20 gigabytes of data to be shared equally among the five members. This means each member is allotted 4 GB (20 GB / 5 members). The total usage for the family last month was 24.6 GB, which is 4.6 GB over the allotted amount. Since Denny went over his share, we can calculate the cost of the extra data Denny used. The cost for each GB of extra data is $10.
First, we need to establish how much data beyond his allowance Denny used. However, the information provided does not specify exactly how much data over his 4GB allowance Denny used, only that the family as a whole went over by 4.6GB. Since the exact amount Denny used over his individual allowance is not provided, we cannot calculate how much he owes. Therefore, the correct answer is:
D. It is not possible to determine how much Denny owes using only the information provided.