document.write( "Question 354442: Tina rides her bike 15m up a hill and then 15m. down the same hill. This complete trip takes 2 hours. If her downhill speed is 20m faster than her uphill speed, how fast does she ride uphill?\r
\n" ); document.write( "\n" ); document.write( "I have these variables and have tried them every which way but loose...
\n" ); document.write( "uphill- distance=15, rate=r, and time=t ;
\n" ); document.write( "downhill- distance=15, rate=r+20, and time=2-t\r
\n" ); document.write( "\n" ); document.write( "No matter what I do, nothing looks workable for me...I think my brain is stuck.
\n" ); document.write( "Thank you, BP \n" ); document.write( "
Algebra.Com's Answer #253275 by Alan3354(69443)\"\" \"About 
You can put this solution on YOUR website!
Tina rides her bike 15m up a hill and then 15m. down the same hill. This complete trip takes 2 hours. If her downhill speed is 20m faster than her uphill speed, how fast does she ride uphill?
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\n" ); document.write( "I'll assume you mean 20 km/hr faster, and that the distances are km, not meters.
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\n" ); document.write( "d = rt (r = uphill rate)
\n" ); document.write( "t = d/r
\n" ); document.write( "2 hr = 15/r + 15/(r+20)
\n" ); document.write( "2*r*(r+20) = 15(r+20) + 15r
\n" ); document.write( "2r^2 + 40r = 15r+300 + 15r
\n" ); document.write( "2r^2 + 10r - 300 = 0
\n" ); document.write( "r^2 + 5r - 150 = 0
\n" ); document.write( "(r + 15)(r - 10) = 0
\n" ); document.write( "r = 10 km/hr uphill, 30 km/hr downhill
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