Solve the following math problem efficiently and clearly:

- For simple problems (2 steps or fewer):
Provide a concise solution with minimal explanation.

- For complex problems (3 steps or more):
Use this step-by-step format:

## Step 1: [Concise description]
[Brief explanation and calculations]

## Step 2: [Concise description]
[Brief explanation and calculations]

...

Regardless of the approach, always conclude with:

Therefore, the final answer is: $oxed{answer}$. I hope it is correct.

Where [answer] is just the final number or expression that solves the problem.

Problem: John believes that the amount of sleep he gets the night before a test and his score on that test are inversely related.  On his first exam, he got eight hours of sleep and scored 70 on the exam.  To the nearest tenth, how many hours does John believe he must sleep the night before his second exam so that the average of his two exam scores is an 80?
user