SOLUTION: Nancy can ride her bike uphill at eight kilometers per hour, and downhill at twelve kilometers per hour.She biked up the hill a certain distance and then biked back down the hill t

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Question 412621: Nancy can ride her bike uphill at eight kilometers per hour, and downhill at twelve kilometers per hour.She biked up the hill a certain distance and then biked back down the hill to her starting point.The entire trip took one hour.How far did she bike up the hill?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
she made 2 trips, one at 8 km/hr, the other at 12 km/hr
The total time was 1 hour
I'll say t = time for uphill trip, 1-t = time for
downhill trip.
1st trip:
d+=+8t
2nd trip:
d+=+12%2A%281+-+t%29
This is 2 equations and 2 unknowns, so it's solvable
Set the d's equal to eachother (both trips are same distance)
8t+=+12+-+12t
20t+=+12
t+=+3%2F5 hr
Now solve for d
d+=+8t
d+=+8%2A%283%2F5%29
d+=+24%2F5 km
d+=+4.8 km
She biked 4.8 km up the hill
check answer:
d+=+12%2A%281+-+t%29
d+=+12%2A%281+-+3%2F5%29
d+=+12%2A%282%2F5%29
d+=+24%2F5
OK