OK this is a homework question. So 5 miiles in 25 minutes, so thats 1 mile in 5 minutes (20 mph). So 20 x 3 = 60 and add 2 miles for the ten minutes should be 62 miles (Seriously if you can average 62 miles in just over 3 hrs you should be in LeTour next year).
Here is a more realistic look at the situation You start off and manage 1 mile in 5 minutes, as the terain is slightly downhill and you have the wind behind you. However, after 25 minutes you come to a 10% gradient hill and your progress drops to about 6 mph for the next 20 minutes. After stopping for some water at the top, you set off on the flat at 18 mph for another 17 minutes, before hitting a slight uphill rise that slows you to 14 mph.
After three hours in the saddle you have gotten into a rhythm, but are still averaging about 14 mph. So you decide to stop for cake. Four and a half hours later you complete your run of 62 miles (Its a 100k charity jobbie) where you make use of the tea and cake facilities of the check in venue where you swap war stories with other riders.