document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1205707>Question 1205707</A>: <I><SPAN STYLE=\"word-break: break-all;\"> When London spent 30 minutes on the elliptical trainer and then did circuit training for 10 minutes, her fitness app said she burned 470 calories. When she spent 10 minutes on the elliptical trainer and 30 minutes circuit training she burned 370 calories. Solve the system:\r<BR>\n" );
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document.write( "{ (30 e + 10 c = 470), (10 e + 30 c = 370) :}\r<BR>\n" );
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document.write( "for e , the number of calories she burned for each minute on the elliptical trainer, and c , the number of calories she burned for each minute of circuit training.\r<BR>\n" );
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document.write( "     e = \r<BR>\n" );
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document.write( "     c = <BR>\n" );
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document.write( "There are many approaches. I'll apply substitution.\r<BR>\n" );
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document.write( "Solve the first equation for the variable c.<BR>\n" );
document.write( "30e+10c = 470<BR>\n" );
document.write( "10c = 470-30e<BR>\n" );
document.write( "c = (470-30e)/10<BR>\n" );
document.write( "c = (470)/10-(30e)/10<BR>\n" );
document.write( "c = 47 - 3e\r<BR>\n" );
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document.write( "Plug that into the other equation.<BR>\n" );
document.write( "10e + 30c = 370<BR>\n" );
document.write( "10e + 30(47 - 3e) = 370<BR>\n" );
document.write( "10e + 1410 - 90e = 370<BR>\n" );
document.write( "10e - 90e = 370 - 1410<BR>\n" );
document.write( "-80e = -1040<BR>\n" );
document.write( "e = -1040/(-80)<BR>\n" );
document.write( "e = 13\r<BR>\n" );
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document.write( "Now we can determine c.<BR>\n" );
document.write( "c = 47 - 3e<BR>\n" );
document.write( "c = 47 - 3*13<BR>\n" );
document.write( "c = 47 - 39<BR>\n" );
document.write( "c = 8\r<BR>\n" );
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document.write( "Summary:<BR>\n" );
document.write( "<font color=red size=4>e = 13<BR>\n" );
document.write( "c = 8</font><BR>\n" );
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