document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=590665>Question 590665</A>: <I><SPAN STYLE=\"word-break: break-all;\"> using ages 12, 40, and 38 write an equation that models how old in years each of you will be, when your ages add up to 150 years old <BR>\n" );
document.write( "(y + a) + (y + a) + (y + a) = 150 yrs.<BR>\n" );
document.write( "(12 + a) + (40 + a) + (38 + a) = 150 yrs.<BR>\n" );
document.write( "90 + a3 = 150 yrs. <BR>\n" );
document.write( "This is what I came up with is it right? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #375232 by </B><A HREF=/tutors/aboutme.mpl?userid=Theo><B>Theo(13342)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Theo><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=Theo><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=375232\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> current ages are 12, 40, and 38<BR>\n" );
document.write( "you want to know in how many years the sum of these ages will be 150.<BR>\n" );
document.write( "let y equal the number of years from now.<BR>\n" );
document.write( "your equation becomes:<BR>\n" );
document.write( "12 + y + 40 + y + 38 + y = 150<BR>\n" );
document.write( "this becomes:<BR>\n" );
document.write( "90 + 3y = 150<BR>\n" );
document.write( "subtract 90 from both sides of this equation to get:<BR>\n" );
document.write( "3y = 60<BR>\n" );
document.write( "divide both sides of this equation by 3 to get:<BR>\n" );
document.write( "y = 20<BR>\n" );
document.write( "in 20 years, the sum of your ages will be 150.<BR>\n" );
document.write( "12 + 20 = 32<BR>\n" );
document.write( "40 + 20 = 60<BR>\n" );
document.write( "38 + 20 = 58<BR>\n" );
document.write( "32 + 60 + 58 = 150<BR>\n" );
document.write( "your equation didn't look quite right but you got the right answer so you must have been thinking correctly even though someone who looked at your equation might not have thought so in the beginning.<BR>\n" );
document.write( "your problem in your equation is you were using y to represent 3 different ages at one time.<BR>\n" );
document.write( "normally that would be shown as 3 different variables.<BR>\n" );
document.write( "assume the following:<BR>\n" );
document.write( "let y1 = the age of the first person<BR>\n" );
document.write( "let y2 = the age of the second person<BR>\n" );
document.write( "let y3 = the age of the third person<BR>\n" );
document.write( "let a = the number of years<BR>\n" );
document.write( "then your equation would have become:<BR>\n" );
document.write( "(y1 + a) + (y2 + a) + (y3 + a) = 150<BR>\n" );
document.write( "this would then have been simplified to:<BR>\n" );
document.write( "y1 + y2 + y3 + 3a = 150<BR>\n" );
document.write( "you could then substitute 12 for y1 and 40 for y2 and 38 for y3 to get:<BR>\n" );
document.write( "12 + 40 + 38 + 3a = 150 which would have led to:<BR>\n" );
document.write( "90 + 3a = 150<BR>\n" );
document.write( "you would then have solved as before using standard equation solving procedures.<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );