document.write( "Question 930733: Genny travels from one elementary school to another and back at a rate of 20 miles per hour one way and 30 miles per hour another way. What is her average rate of speed for both trips? \n" ); document.write( "
Algebra.Com's Answer #565250 by ankor@dixie-net.com(22740)\"\" \"About 
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Genny travels from one elementary school to another and back at a rate of 20 miles per hour one way and 30 miles per hour another way.
\n" ); document.write( " What is her average rate of speed for both trips?
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\n" ); document.write( "let d = the one way distance of the trip
\n" ); document.write( "let a = the average speed for the round trip
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\n" ); document.write( "Write a time equation; time = dist/speed
\n" ); document.write( "to time + return time = total time
\n" ); document.write( "\"d%2F20\" + \"d%2F30\" = \"%282d%29%2Fa\"
\n" ); document.write( "multiply equation by 60a; cancel the denominators
\n" ); document.write( "3ad + 2ad = 60(2d)
\n" ); document.write( "5ad = 120d
\n" ); document.write( "divide both sides by d
\n" ); document.write( "5a = 120
\n" ); document.write( "a = 120/5
\n" ); document.write( "a = 24 mph is the average for the round trip
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