document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1147349>Question 1147349</A>: <I><SPAN STYLE=\"word-break: break-all;\"> David and Amy start at the same point and begin biking in different directions. David is biking west at a speed of 17 miles per hour. Amy is biking south at a speed of 15 miles per hour. After how many hours will they be exactly 23 miles apart? Round your answer to two decimal places. \r<BR>\n" );
document.write( "\n" );
document.write( "I have tried setting it up as 15x+17x=23 (my answer was 0.72 and it was wrong).  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #768665 by </B><A HREF=/tutors/aboutme.mpl?userid=greenestamps><B>greenestamps(13198)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=greenestamps><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=greenestamps><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=768665\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <br><BR>\n" );
document.write( "15x+17x=23 would be a valid equation if the two of them were biking in opposite directions, like east and west, or north and south.<br><BR>\n" );
document.write( "But they are biking in directions that differ by 90 degrees.<br><BR>\n" );
document.write( "That means the paths of the two of them, along with the distance between them, form a right triangle.  The distances the two travel (your 15x and 17x) are the legs; the distance between them is the hypotenuse.<br><BR>\n" );
document.write( "Then you can use the Pythagorean Theorem to find when the distance between them will be 23 miles:<br><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=a%5E2%2Bb%5E2+=+c%5E2 ALIGN=MIDDLE  ALT=\"a%5E2%2Bb%5E2+=+c%5E2\"   DISABLED_style= \"max-width:90%; height:auto;\" ><br><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%2815x%29%5E2+%2B+%2817x%29%5E2+=+%2823%29%5E2 ALIGN=MIDDLE  ALT=\"%2815x%29%5E2+%2B+%2817x%29%5E2+=+%2823%29%5E2\"   DISABLED_style= \"max-width:90%; height:auto;\" ><br><BR>\n" );
document.write( "Use a calculator.... </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );