SOLUTION: Every day Jane and Bill both drive to a parking lot, and then take the subway to get to work. Jane drives 90 km at 60 km/h, and then takes a northbound subway that averages 28 km/h

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: Every day Jane and Bill both drive to a parking lot, and then take the subway to get to work. Jane drives 90 km at 60 km/h, and then takes a northbound subway that averages 28 km/h      Log On

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Question 1097584: Every day Jane and Bill both drive to a parking lot, and then take the subway to get to work. Jane drives 90 km at 60 km/h, and then takes a northbound subway that averages 28 km/h for 21 km while Bill drives 20 km at 45 km/h and then takes a southbound subway that averages 18 km/h for 30 km. It takes each of them 25 minutes to change from car to subway, and they arrive at the same destination at 8:30 am. At what time does the earliest of them leave home?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
I can run this backwards, and place them
both at the same time at destination
Janes time:
+t%5B1%5D+=+90%2F60+
+t%5B1%5D+=+1.5+
------------------
+t%5B2%5D+=+21%2F28+
+t%5B2%5D+=+.75+
------------------
Bill's time:
+t%5B1%5D+=+20%2F45+
+t%5B1%5D+=+.4444+
------------------
+t%5B2%5D+=+30%2F18+
+t%5B2%5D+=+1.667+
------------------
Add +25%2F60+=+.41667+
to each one's time
--------------------------
Jane's time:
+1.5+%2B+.75+%2B+.41667+=+2.667+
Bill's time:
+.4444+%2B+1.667+%2B+.41667+=+2.5278+
--------------------------------------
Jane's time is longer, so she left the earliest at
8:30 - ( 2 hrs + (2/3)*60 )
8:30 - 2hrs - 40 min
--------------------
This is 6:30 - 40 min or
6:00 - 10 min or
5:50
-------------------------
definitely get a second opinion if needed
check the math