SOLUTION: Ethan can run twice as fast as he can walk. If after running two hours and then walking two hours Ethan has moved 21 miles, how fast does Ethan run? How fast does he walk?

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Question 1074357: Ethan can run twice as fast as he can walk. If after running two hours and then walking two hours Ethan has moved 21 miles, how fast does Ethan run? How fast does he walk?
Answer by josgarithmetic(39630) About Me  (Show Source):
You can put this solution on YOUR website!
Ethan walks at r miles per hour.

2r%2A2%2Br%2A2=21

r=21%2F6=7%2F2

r=3%261%2F2-----walking
-
2r=7------running