document.write( "Question 1190897: Sam jogged to Larry's house at 8 miles per hour and borrowed Larry's scooter, riding back at 20 miles per hour. If the round trip took 7 hours, how far is it to Larry's house? Write a distance equation \n" ); document.write( "
Algebra.Com's Answer #822625 by Alan3354(69443)\"\" \"About 
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Sam jogged to Larry's house at 8 miles per hour and borrowed Larry's scooter, riding back at 20 miles per hour. If the round trip took 7 hours, how far is it to Larry's house? Write a distance equation
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\n" ); document.write( "The average speed of a round trip is \"2%2Ar%5B1%5D%2Ar%5B2%5D%2F%28r%5B1%5D%2Br%5B2%5D%29\" where r1 and r2 are the 2 speeds.
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\n" ); document.write( "= 2*8*20/(8+20) = 320/28 = 80/7 mi/hr
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\n" ); document.write( "d = r*t = (80/7)*7 = 80 miles RT, 40 miles each way
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\n" ); document.write( "The formula is similar to parallel work, parallel resistance, etc. and is easy to remember.\r
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