SOLUTION: i need ur help on travel and distance problems plzzzzzz...... a motorist drove 150 miles on the highway before driving 50 miles on the mountain roads.the rate speed on the highw

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Question 845917: i need ur help on travel and distance problems plzzzzzz......
a motorist drove 150 miles on the highway before driving 50 miles on the mountain roads.the rate speed on the highway was 3 times the rate on the mountain roads.the time spent travelling the 200 miles was 5 hours .find the rate of the motorist in the highway?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +t+ = time in hrs spent on mountain roads
+5+-+t+ = time in hrs spent on highway
Let +s+ = motorist's speed in mi/hr on mountain roads
+3s+ = motorist's speed in mi/hr on highway
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For mountain roads:
(1) +50+=+s%2At+
For highway:
(2) +150+=+3s%2A%28+5+-+t+%29+
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(2) +150+=+15s+-+3s%2At+
Substitute (1) into (2)
(2) +150+=+15s+-+3%2A50+
(2) +150+=+15s+-+150+
(2) +15s+=+300+
(2) +s+=+20+
and
+3s+=+60+
The motorist's rate on the highway was 60 mi/hr
check:
(1) +50+=+s%2At+
(1) +50+=+20%2At+
(1) +t+=+2.5+
and
(2) +150+=+3s%2A%28+5+-+t+%29+
(2) +150+=+60%2A%28+5+-+t+%29+
(2) +150+=+300+-+60t+
(2) +60t+=+150+
(2) +t+=+15%2F6+
(2) +t+=+2.5+
OK