document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=749509>Question 749509</A>: <I><SPAN STYLE=\"word-break: break-all;\"> the county's new asphalt paving machine can surface one mile of highway in 10 hours. A much older machine can surface one mile in 18 hours. How long will it take them to surface one mile of highway, working together? How long will it take them to surface 20 miles? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #456024 by </B><A HREF=/tutors/aboutme.mpl?userid=FrankM><B>FrankM(1040)</B></A><img src=\"/images/stars/stars-12.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=FrankM><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/cgi-bin/show-face.mpl?user=FrankM><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=456024\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> First machine can do 1/10 mile per hour, Second machine, 1/18 mile per hour. \r<BR>\n" );
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document.write( "1/10 + 1/18 = 9/90 + 5/90 = 14/90 = 7/45 miles per hour. \r<BR>\n" );
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document.write( "A full mile would take 45/7 hours or ANS = 6 3/7 hours. \r<BR>\n" );
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document.write( "Multiply by 20,  900/7 = ANS = 128 4/7 hours. \r<BR>\n" );
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document.write( "Note - another tutor offered a short cut for this type of problem. \r<BR>\n" );
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document.write( "A 10 hr worker and a 18 hour worker combined will do a job in (10*18)/(10+18) hours or 180/28 which is the same 45/7 hours I calculate. <BR>\n" );
document.write( "To be sure you get the numerator and denominator correct, be sure the answer makes sense. 2 10 hour workers would combine to do a job in 5 hours, so the 10 and 18 combine must be between 5 and 10.  </SPAN>\n" );
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