SOLUTION: two cars leave the same city at the same time.Both traveling opposite directions. One car is traveling 5 miles faster than the other. After 3 hours both two cars are 393 miles apa

Algebra ->  Length-and-distance -> SOLUTION: two cars leave the same city at the same time.Both traveling opposite directions. One car is traveling 5 miles faster than the other. After 3 hours both two cars are 393 miles apa      Log On


   



Question 876993: two cars leave the same city at the same time.Both traveling opposite directions. One car is traveling 5 miles faster than the other. After 3 hours both two cars are 393 miles apart. Find the speed of both cars.
Found 2 solutions by Alan3354, josmiceli:
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
two cars leave the same city at the same time.Both traveling opposite directions. One car is traveling 5 miles faster than the other. After 3 hours both two cars are 393 miles apart. Find the speed of both cars.
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"Both traveling opposite directions." ?? Think about that.
Try "traveling in opposite directions."
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If they go in opposite directions, their speeds are added.
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d = r*t
r = d/t = 393/3
The sum of their speeds = 131 mi/hr
The difference is 5 mi/hr
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r1 + r2 = 131
r1 - r2 = 5
---------------- Add

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
You can think of one cart as standing still
and the other car traveling at the sum
of their speeds
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Let +s+ = the speed of the slower car in mi/hr
+s+%2B+5+ = the speed of the faster car in mi/hr
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+393+=+%28+s+%2B+s+%2B+5+%29%2A3+
+393+=+%28+2s+%2B+5+%29%2A3+
+393+=+6s+%2B+15+
+6s+=+378+
+s+=+63+
+s+%2B+5+=+68+
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Their speeds are 63 mi/hr and 68 mi/hr
check:
+d%5B1%5D+=+s%2At+
+d%5B1%5D+=+63%2A3+
+d%5B1%5D+=+189+
and
+d%5B2%5D+=+68%2A3+
+d%5B2%5D+=+204+
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+d%5B1%5D+%2B+d%5B2%5D+=+393+
+189+%2B+204+=+393+
+393+=+393+
OK