Find a spot at a whiteboard and complete the following:
There are two malls that open at the same time.
The number of people in Mall A is modeled by -t² +9t + 36,
and the number of people in Mall B is modeled by - t² + 11t + 12,
where t represents the number of hours since the mall opened.
A) Write an expression that models how many more people are in Mall A than Mall B at time t.
B) How many people are in Mall A when t = 3 hours?