Noah makes a round trip commute to work each day by car. His trip in the morning is quicker because he leaves before traffic gets bad, so his speed is 15 miles per hour faster in the morning which makes his 8 mile commute take 30 minutes less time than on the way home when traffic is bad and he drives more slowly.
a. What is Noah's average speed in both directions?
b. If he could leave even earlier in the morning and drive an additional 10 miles per hour faster, how much time would that save him on his overall daily commute?