To simplify questions, you answer them.
ANSWER
$28
EXPLANATION
The profit function is given as:

where x is the price of the T-shirt in dollars.
To find the profit on a T-shirt whose price is $15, we substitute x=15 into the function and simplify.

We simplify to get:



It depends on the definition of day, solar day or stellar day.
Explanation: Solar day: 1 day = 24h
7 days = 168h
What is 3 times the number?
3*66 = 198