Question 505827
5080 feet = 1 miles
1 feet = 1/5080
1 feet =  0.00019685 miles
18 feet = 18*0.00019685 miles 
18 feet=0.0035433 miles
1 hour = 60*60 = 3600 second
1/3600 hour = 1 second
1 second = 1/3600 hours
1 second = 0.000277778 hours
2 second = 2*0.000277778 hours
2 second = 0.000555556 hours

Speed = Distance /  time
Speed = 18 feet / 2 seconds
Speed = 0.0035433 miles / 0.000555556 hours
Speed = 0.0035433/0.000555556 mph
Speed = 6.377934898 mph
Speed = 6.38 mph