document.write( "Question 309272: You drive 220 miles to see a friend. The return trip takes 20 minutes less than the original trip, and your average speed is 5 miles per hour faster. What is your average speed on the return trip? \n" ); document.write( "
Algebra.Com's Answer #221180 by ankor@dixie-net.com(22740)\"\" \"About 
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You drive 220 miles to see a friend.
\n" ); document.write( " The return trip takes 20 minutes less than the original trip, and your average speed is 5 miles per hour faster.
\n" ); document.write( "What is your average speed on the return trip?
\n" ); document.write( ":
\n" ); document.write( "Let s = return trip speed
\n" ); document.write( "then
\n" ); document.write( "(s-5) = original trip speed
\n" ); document.write( ":
\n" ); document.write( "Change 20 min to 1/3 hr
\n" ); document.write( ":
\n" ); document.write( "Write a time equation, Time = dist/speed
\n" ); document.write( "Original trip time - return trip time = 1/3 hr
\n" ); document.write( "\"220%2F%28s-5%29\" - \"220%2Fs\" = \"1%2F3\"
\n" ); document.write( "multiply equation by 3s(s-5) results:
\n" ); document.write( "3s(220) - 3(s-5)*220 = s(s-5)
\n" ); document.write( "660s - 660(s - 5) = s^2 - 5s
\n" ); document.write( "660s - 660s + 3300 = s^2 - 5s
\n" ); document.write( "0 = s^2 - 5s - 3300
\n" ); document.write( "Factors to
\n" ); document.write( "(s-60)(s+55) = 0
\n" ); document.write( "s = +60 mph \n" ); document.write( "
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