Answer:
13.3f
Step-by-step explanation:

First, replace the numerator with the parentheses.
Second, multiply both sides by 3.
Third, multiply 2 × 3 to get 6.
Fourth, take away 15 from each side.
Fifth, simplify -6 - 15 to get -21.

Answer:
n = -21
15 minutes is one quarter of an hour, so the number of people accommodated in an hour would be 4 x 55 = 220 people per hour