SOLUTION: pedro can drive 4 times as fast as luis can ride his bicycle. if it takes luis 3 hrs longer than pedro to travel 36 miles, how fast can luis ride his bicycle?

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Question 731514: pedro can drive 4 times as fast as luis can ride his bicycle. if it takes luis 3 hrs longer than pedro to travel 36 miles, how fast can luis ride his bicycle?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +s+ = Luis's speed in mi/hr
+4s+ = Pedro's speed in mi/hr
Let +t+ = Pedro's time in hrs to travel 36 mi
+t+%2B+3+ = Luis's time in hrs to travel 36 mi
-------------
Pedro's equation:
(1) +36+=+%284s%29%2At+
Luis's equation:
(2) +36+=+s%2A%28+t+%2B+3+%29+
--------------------
(1) +t+=+9%2Fs+
(2) +36+=+s%2A%28+9%2Fs+%2B+3+%29+
(2) +36+=+9+%2B+3s+
(2) +3s+=+27+
(2) +s+=+9+
Luis's speed is 9 mi/hr
check:
(1) +t+=+9%2Fs+
(1) +t+=+9%2F9+
(1) +t+=+1+ hr
and
(2) +36+=+9%2A%28+t+%2B+3+%29+
(2) +36+=+9t+%2B+27+
(2) +9t+=+9+
(2) +t+=+1+ hr
OK