Im wondering the same thing i have this question to
For this case we have the following quadratic functions:
Revenue: 
Cost: 
Then, we observe that the profit is given by the following mathematical relationship:

Substituting values we have:

Making the corresponding calculations we have:

Answer:
An expression that represents the profit is:

Answer:
19.5 miles per hour
Step-by-step explanation:
We need to change 20 minutes to hours
1 hours = 60 minutes
20 minutes * 1 hour/60 minutes = 1/3 hour
To find miles per hour we take the miles and divide by hours
6.5 miles
---------------- = 19.5 miles per hour
1/3 hours