SOLUTION: Ellen and Kate leave school at 3:00 p.m. They race to the library on their bikes. Kate is going 9 mph and Ellen is going 12 mph. Ellen got to the library 15 minutes before Kate. Wh

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Question 1094619: Ellen and Kate leave school at 3:00 p.m. They race to the library on their bikes. Kate is going 9 mph and Ellen is going 12 mph. Ellen got to the library 15 minutes before Kate. What time did Kate get to the library?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +d+ = distance in miles from
school to library
Let +t+ = time in hrs that Kate took
to get top the library
-----------------------------------
Kate's equation:
(1) +d+=+9t+
Ellen's equation:
(2) +d+=+12%2A%28+t+-+.25+%29+
------------------------
Set (1) = (2)
+9t+=+12%2A%28+t+-+.25+%29+
+9t+=+12t+-+3+
+3t+=+3+
+t+=+1+
and
+t+-+.25+=+.75+
-------------------------
Kate got to the library at 3 PM plus 1 hr = 4 PM
-------------------------
check:
(1) +d+=+9t+
(1) +d+=+9+
and
(2) +d+=+12%2A%28+t+-+.25+%29+
(2) +d+=+12%2A.75+
(2) +d+=+9+
OK