document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1186453>Question 1186453</A>: <I><SPAN STYLE=\"word-break: break-all;\"> ___________10. The sum of Mario’s age and Luigi’s age is 80. Four years ago, Mario is thrice as old as Luigi. How old is Mario now? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #817385 by </B><A HREF=/tutors/aboutme.mpl?userid=greenestamps><B>greenestamps(13200)</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=817385\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <br><BR>\n" );
document.write( "The solution from the other tutor is fine; I would set it up differently.<br><BR>\n" );
document.write( "Given that Mario was 3 times as old as Luigi 4 years ago, I would do this:<br><BR>\n" );
document.write( "Let x = Luigi's age 4 years ago<BR>\n" );
document.write( "Then 3x = Mario's age 4 years ago<br><BR>\n" );
document.write( "Given that the sum of their ages now is 80, do some simple mental arithmetic to determine that 4 years ago the sum of their ages was 72.  Then<br><BR>\n" );
document.write( "3x+x=72<BR>\n" );
document.write( "4x=72<BR>\n" );
document.write( "x=18<br><BR>\n" );
document.write( "Their ages 4 years ago were<BR>\n" );
document.write( "Luigi = x = 18<BR>\n" );
document.write( "Mario = 3x = 54<br><BR>\n" );
document.write( "ANSWER: Mario's age now is 54+4 = 58<br><BR>\n" );
document.write( "Note setting the problem up that way leads to algebra that is simpler than in the solution from the other tutor.<br><BR>\n" );
document.write( "And if formal algebra is not required, and/or if the speed of reaching a solution is important -- as in a timed math competition -- solving the problem by this method can be done mentally in far less time than with the formal method shown by the other tutor.<br><BR>\n" );
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document.write( "</TD></TR></TABLE>\n" );