SOLUTION: During the first part of a trip, Adrian drove 50 miles at a certain speed. Adrian drives another 50 miles on the second part of the trip at a speed 5 mph faster. Driving time for t

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Question 1128345: During the first part of a trip, Adrian drove 50 miles at a certain speed. Adrian drives another 50 miles on the second part of the trip at a speed 5 mph faster. Driving time for the entire trip was 88 mins. Find the rate at which Adrian drove during the first part of the trip.
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +s+ = speed for 1st part of trip
+s+%2B+5+ = speed for 2nd part of trip
Let +t+ = time in hrs for 1st part of trip
+88%2F60+-+t+ = time in hrs for 2nd part
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1st part:
(1) +50+=+s%2At+
2nd part:
(2) +50+=+%28+s+%2B+5+%29%2A%28+22%2F15+-+t+%29+
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(2) +%28+22%2F15+%29%2As+%2B+22%2F3+-+s%2At+-+5t+=+50+
(2) +22s+%2B+110+-+15s%2At+-+75t+=+750+
(2) +15s%2At+%2B+75t+=+22s+-+640+
(2) +t%2A%28+15s+%2B+75+%29+=+22s+-+640+
(2) +t+=+%28+22s+-+640+%29%2F%28+15s+%2B+75+%29+
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(1) +50+=+s%2At+
(1) +50+=+s%2A%28+22s+-+640+%29%2F%28+15s+%2B+75+%29+
(1) +50%2A%28+15s+%2B+75+%29+=+s%2A%28+22s+-+640+%29+
(1) +750s+%2B+3750+=+22s%5E2+-+640s+
(1) +22s%5E2+-+1390s+-+3750+=+0+
(1) +11s%5E2+-+695s+-+1875+=+0+
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Solve using quadratic formula.