SOLUTION: Two cars start at the same location and travel in the same direction at average speeds of 30 miles per hour and 45 miles per hour. How much time must elapse before the two cars are

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Question 713024: Two cars start at the same location and travel in the same direction at average speeds of 30 miles per hour and 45 miles per hour. How much time must elapse before the two cars are 13 miles apart?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Faster car's equation:
(1) +d+=+45t+
Slower car's equation:
(2) +d+-+13+=+30t+
-------------------
Substitute (1) into (2)
(2) +45t+-+13+=+30t+
(2) +15t+=+13+
(2) +t+=+13%2F15+ hrs
(2) +t+=+%2813%2F15%29%2A60+=+52+ min
-------------
check:
(1) +d+=+45%2A%2813%2F15%29+
(1) +d+=+39+ mi
and
(2) +d+-+13+=+30%2A%2813%2F15%29+
(2) +d+=+13+%2B+26+
(2) +d+=+39+ mi
OK