Question 895156
7' in 1/3 of a second? 
How fast would they walk in a full second?  3x as far (1/3 + 1/3 + 1/3)
In one second, they walk 21'
21' in one second means 5x as much in 5 seconds
21' * 5 = 105'
That's REALLY fast.
(Math was not my best subject either ;-))