SOLUTION: Marie started jogging at 08:30 at 9 km/h 15 minutes later, Heather starts jogging at 12 km/h how long did it take Heather to catch up with Marie?

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Question 417598: Marie started jogging at 08:30 at 9 km/h 15 minutes later, Heather starts jogging at 12 km/h how long did it take Heather to catch up with Marie?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
How far did Marie get in 1/4 hr?
d%5B1%5D+=+9%2A%281%2F4%29
d%5B1%5D+=+9%2F4 km
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The equation for Heather is:
d%5B2%5D+=+12%2At%5B2%5D
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The equation for Marie is:
d%5B2%5D+-+9%2F4+=+9%2At%5B2%5D
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Note that d%5B2%5D is the distance Heather has to go
to catch up with Marie
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By substitution:
12t%5B2%5D+-+9%2F4+=+9t%5B2%5D
+3t%5B2%5D+=+9%2F4+
+t%5B2%5D+=+3%2F4
Note that t%5B2%5D is the time from 8:30 + 15 min to the time they meet
1%2F4+%2B+3%2F4+=+1+ hr
Heather catches Marie 1 hr after 8:30, or 9:30