document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=512387>Question 512387</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Hi! This is a problem from me test. I really need help. Thank you<BR>\n" );
document.write( "On a trip Jennifer noticed that her car averaged 21mi/gal of gas except for the days she used the air conditioning, and the it averaged only 16mi/gal. If she used 91 gal of gas to drive 1751 mi, how many of those miles did she use the air conditioning? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #342619 by </B><A HREF=/tutors/aboutme.mpl?userid=Sarah900><B>Sarah900(12)</B></A><img src=\"/images/stars/stars-06.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Sarah900><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=342619\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> (mileage with AC (mi/gal))*(gas used with AC(gal))+ (mileage without AC (mi/gal))*(gas used without AC(gal))=total miles traveled (miles)<BR>\n" );
document.write( "Note how the units cancel out to leave you with miles<BR>\n" );
document.write( "Assign x for one of the missing elements.  We'll say the gas Jennifer used when she was using AC= x.  Since she used 91 gallons total the expression that would tell you what she used without AC= 91-x. <br> <BR>\n" );
document.write( "Plug in what you know and solve for x<BR>\n" );
document.write( "(21)*(x)+(16)*(91-x)=1751<BR>\n" );
document.write( "21x+1456-16x=1751<BR>\n" );
document.write( "5x+1456=1751<BR>\n" );
document.write( "5x=295<BR>\n" );
document.write( "x=59<br><BR>\n" );
document.write( "So she used 59 gallons when she had AC.  To find how much she used without <BR>\n" );
document.write( "91-59=32<br><BR>\n" );
document.write( "You can find how many miles she drove during each by multiplying the mileage with the corresponding number of gallons. So...<BR>\n" );
document.write( "21*59=1239<BR>\n" );
document.write( "16*32=512 </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );