Let Y be your velocity rate and F be the velocity rate of your friend. Since your friend rides his bike 2 mi/h slower than you, we can write:
Now, in 10 minutes, your friend travel 8 miles. Then, his velocity rate is
but, in order to use this result, we need to convert miles/minutes into miles/hour. Lets convert it:
Then, the friend's velocity rate is
Finally, by substituting this result into equation (a), we have
Therefore, the answers are: