SOLUTION: During rush hour, Fernando can drive 25 miles using the side roads in the same time that it takes to travel 20 miles on the freeway. If Fernando's rate on the side roads is 9 mi/h

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Question 672809: During rush hour, Fernando can drive 25 miles using the side roads in the same time that it takes to travel 20 miles on the freeway. If Fernando's rate on the side roads is 9 mi/h faster than his rate on the freeway, find his rate on the side roads?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +r+ = his rate on the freeway
+r+%2B+9+ = his rate on side roads
Let +t+ = time for both
----------
On side roads:
(1) +25+=+%28+r+%2B+9+%29%2At+
On freeway:
(2) +20+=+r%2At+
---------------
(1) +25+=+r%2At+%2B+9t+
Substitute (2) into (1)
(1) +25+=+20+%2B+9t+
(1) +9t+=+5+
(1) +t+=+5%2F9+
--------------
On side roads:
(1) +25+=+%28+r+%2B+9+%29%2A%285%2F9%29+
(1) +25+=+%285%2F9%29%2Ar+%2B+5+
(1) +%285%2F9%29%2Ar+=+20+
(1) +r+=+%289%2F5%29%2A20+
(1) +r+=+36+
+r+%2B+9+=+45+
His rate on side roads is 45 mi/hr
check:
(2) +20+=+r%2At+
(2) +20+=+36%2A%285%2F9%29+
(2) +180+=+180+