Simple Arithmetic

I went for a nice long bike ride on Saturday and stopped in a town called Alvarado, VA. I was looking for some water after I did a very graceful front flip off of my bike and landed on my camelbak causing 3L of water to run down my back...There was a very nice old man sitting on the front porch and he said

"Where you coming from?"

"Whitetop, VA."

"How far is that?"

"Not sure"

"Let me find a map." He went to look for a map and meanwhile I saw one posted on the window. I was on a trail and Alvarado is at Mile Marker 9. Whitetop is at mile marker 34. Hmm...how far away am I?

"Well here's a map I rustled up of this here trail. It looks like Alvarado here is around mile marker 9 and that Whitetop is all the way at mile marker 34. So if you went to Damascus it would be about 8 miles, then you'd head up to here which would be 10 more miles and then you'd head on to Whitetop which looks like it would be about 6 or so miles. So that's 8 and 10 and hmmm...yeah I'd say you'd be about 20 something miles away."

Thanks. I had figured 34-9 about 5 minutes ago. He was a nice enough guy and normally I would be nicer, but he never let me have any water either.