Doug entered a canoe race. he rowed 3 1/2 miles in 1/2 hour. what is his average speed in miles per hour?

3 1/2 miles = 7/2 miles

1/2 hours = 30 minutes

So,

In 30 mins, travelled 7/2 miles

In 1 min, travelled 7/2 : 30 = 7/2 * 1/30 = (7*1) / (2*30) = 7/60 miles

In 60 mins, travelled (7*60) / 60 miles = 420/60 miles = 7 miles.

Hence, the speed is 7 miles per hour. Anything else

Average speed = total distance / total time ...

s=3.5/0.5=7mph