Well first, let's establish that the rate of change (r) is equivalent to the distance (d) divided by the time (t), which is: r=d/t.
So let's plug in some numbers!
r=(1 mile)/(30 seconds), which is 1/30 miles per second!
r=(5 miles)/(150 seconds), which is also 1/30 miles per second!
I'm not sure if you're supposed to estimate your response, so I would just put 1/30 in the answer box!