Rich, this is the solution:
Step 1: Let's find the area of each rectangle, as follows:
Length of the rectangle = 3,444 feet
Width of the rectangle = 11 feet
Area = 3,444 * 11
Area = 37,884 feet²
Step 2: Let's duplicate the area because people will stand at both sides of the avenue, in consequence:
Total area = 2 * 37,884
Total area = 75,768
Step 3: For finding the size of the crowd, we divide:
Total area/Area occupied by each person
75,768/2.5 = 30,308 (rounding to the nearest whole person)
The size of the crowd is 30,308 people, Rich. But we don't know if they're all adults or they are also children, that information was not given.