Average Speed if 450 miles in 6 hours

Question

If David wants to drive to his friend's house, which is 450 miles away, in 6 hours, what is the average speed David has to drive at?

Answer 1

450/6 = 75 mph

= average speed

450 miles in 6 hours = 75 miles in 1 hour

75/1 =450/6, ratio of miles to hours is a constant

Answer 2

Distance=rate\times time

Plug in the the values for distance and time, and solve for rate.

450 = r\ 6

and 

r = 75 mph