SOLUTION: Two cars are traveling on the same road and start from the same location. When the blue car starts the trip the red car has already traveled 40 miles. The speed of the blue car i

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Question 751119: Two cars are traveling on the same road and start from the same location. When the blue car starts the trip the red car has already traveled 40 miles. The speed of the blue car is 70 mph and the speed of the red car is 50 mph
a). How long does it take the blue car to catch the red car?
b). How far have they traveled from the starting point when the blue car catches the red car?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +t+ = the time in hours it takes blue car to catch red car
Let +d+ = the distance in miles blue car has to travel to catch red car
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Blue car's equation:
(1) +d+=70t+
Red car's equation:
(2) +d+-+40+=+50t+
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Substitute (1) into (2)
(2) +70t+-+40+=+50t+
(2) +20t+=+40+
(2) +t+=+2+
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(1) +d+=+70t+
(1) +d+=+70%2A2+
(1) +d+=+140+
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a). It takes 2 hours for the blue car to catch the red car
b). They traveled 140 miles from the starting point when the blue car catches the red car
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check answer:
(2) +d+-+40+=+50t+
(2) +140+-+40+=+50%2A2+
(2) +100+=+10-0+
OK