SOLUTION: Two cars leave a gas station at the same time, one traveling north and the other south. The northbound car travels at 50 mph. After 3 hours the cars are 345 miles apart. How fast i

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Question 778228: Two cars leave a gas station at the same time, one traveling north and the other south. The northbound car travels at 50 mph. After 3 hours the cars are 345 miles apart. How fast is the southbound car traveling?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
The cars are separating at the sum of their speeds
Let +r+ = the rate of the southbound car
I can say:
+345+=+%28+50+%2B+r+%29%2A3+
+345+=+150+%2B+3r+
+3r+=+195+
+r+=+65+
The southbound car is traveling at 65 mi/hr
check:
Northbound car:
+d%5B1%5D+=+50%2A3+
+d%5B1%5D+=+150+
Southbound car:
+d%5B2%5D+=+65%2A3+
+d%5B2%5D+=+195+
and
+150+%2B+195+=+345+
OK