SOLUTION: good morning, this is my questiion. Dave can hike on level ground 3 miles an hour faster that he can on uphill terrain.Yesterday, he hiked 27 miles spending 2 hours on level ground

Algebra ->  Average -> SOLUTION: good morning, this is my questiion. Dave can hike on level ground 3 miles an hour faster that he can on uphill terrain.Yesterday, he hiked 27 miles spending 2 hours on level ground      Log On


   

Question 1097143: good morning, this is my questiion. Dave can hike on level ground 3 miles an hour faster that he can on uphill terrain.Yesterday, he hiked 27 miles spending 2 hours on level ground and 5 hours on uphill terrain. find his average speed on level ground.
Thanks!

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Average speed is ALWAYS:
[ distance traveled ] / [ time spent traveling ]
Let +s+ = his speed on uphill terrain
+s+%2B+3+ = his speed on level ground
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+s%2A5+%2B+%28+s+%2B+3+%29%2A2+=+27+
+5s+%2B+2s+%2B+6+=+27+
+7s+=+21+
+s+=+3+ mi/hr
and
+s+%2B+3+=+6+ mi/hr
--------------------------
His average speed on level ground was 6 mi/hr
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check:
+s%2A5+%2B+%28+s%2B3+%29%2A2+=+27+
+3%2A5+%2B+6%2A2+=+27+
+15+%2B+12+=+27+
+27+=+27+
OK