document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1121008>Question 1121008</A>: <I><SPAN STYLE=\"word-break: break-all;\"> when the father was the same age as his daughter is now, she was 4 years old. when the daughter becomes the same age as her father is now, her father will be 79 years old. what are their ages </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #736739 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=736739\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> good one.\r<BR>\n" );
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document.write( "let f = the father's age now.<BR>\n" );
document.write( "let d = the daughter's age now.\r<BR>\n" );
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document.write( "not sure whether i needed to do it this way, but it worked.\r<BR>\n" );
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document.write( "when the father was the same age as his daughter is now, she was 4 years old.\r<BR>\n" );
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document.write( "let x equal the number of years when the father was the same age as his daughter is now.\r<BR>\n" );
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document.write( "the equations for that are:\r<BR>\n" );
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document.write( "f - x = d<BR>\n" );
document.write( "d - x = 4\r<BR>\n" );
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document.write( "solve for x in the second equation to get:\r<BR>\n" );
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document.write( "x = d - 4\r<BR>\n" );
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document.write( "replace x with d - 4 in the first equation to get:\r<BR>\n" );
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document.write( "f - x = d becomes f - (d - 4) = d<BR>\n" );
document.write( "simplify to get f - d + 4 = d<BR>\n" );
document.write( "add d and subtract 4 from both sides of this equation to get:\r<BR>\n" );
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document.write( "f = 2d - 4 ***** hold on to this for later.\r<BR>\n" );
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document.write( "when the daughter becomes the same age as her father is now, her father will be 79 years old.\r<BR>\n" );
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document.write( "let y equal the number of years when the daughter is the same age as the father is now.\r<BR>\n" );
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document.write( "the equations for that are:\r<BR>\n" );
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document.write( "d + y = f<BR>\n" );
document.write( "f + y = 79\r<BR>\n" );
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document.write( "solve for y in the second equation to get:\r<BR>\n" );
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document.write( "y = 79 - f\r<BR>\n" );
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document.write( "replace y in the first equation with that to get:\r<BR>\n" );
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document.write( "d + y = f becomes d + (79 - f) = f<BR>\n" );
document.write( "simplify tto get d + 79 - f = f<BR>\n" );
document.write( "add f to both sides 79 from both sides of this equation to get:\r<BR>\n" );
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document.write( "d = 2f - 79 ***** hold onto this for later.\r<BR>\n" );
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document.write( "later:\r<BR>\n" );
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document.write( "the equations you held are:\r<BR>\n" );
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document.write( "f = 2d - 4<BR>\n" );
document.write( "d = 2f - 79\r<BR>\n" );
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document.write( "replace d with 2f - 79 in the first equation to get:\r<BR>\n" );
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document.write( "f = 2 * (2f - 79) - 4<BR>\n" );
document.write( "simplify to get:<BR>\n" );
document.write( "f = 4f - 158 - 4<BR>\n" );
document.write( "combine like terms to get:<BR>\n" );
document.write( "d = 4f - 162<BR>\n" );
document.write( "add 162 and subtract d from both sides of this euation to get:<BR>\n" );
document.write( "162 = 3f<BR>\n" );
document.write( "solve for f to get:\r<BR>\n" );
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document.write( "f = 54\r<BR>\n" );
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document.write( "go back to f = 2d - 4 and replace f with 54 to get:<BR>\n" );
document.write( "54 = 2d - 4<BR>\n" );
document.write( "add 4 to both sides of this equation to get 58 = 2d<BR>\n" );
document.write( "solve for d to get d = 58/2 = 29\r<BR>\n" );
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document.write( "d = 29\r<BR>\n" );
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document.write( "you now have f = 54 and d = 29\r<BR>\n" );
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document.write( "go back to f - x = d and replace f with 54 and d with 29<BR>\n" );
document.write( "solve for x to get x = 54 - 29 = 25\r<BR>\n" );
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document.write( "25 years ago, the father was 54 - 25 = 29<BR>\n" );
document.write( "25 years ago, the daughter was 29 - 25 = 4\r<BR>\n" );
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document.write( "your first 2 equations of:\r<BR>\n" );
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document.write( "f - x = d<BR>\n" );
document.write( "d - x = 4\r<BR>\n" );
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document.write( "hold true when f = 54 and d = 29 and x = 25\r<BR>\n" );
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document.write( "54 - 25 = 29 which is the daughter's age now.<BR>\n" );
document.write( "25 - 25 = 4 which is how old the daughter was when the father was her age.\r<BR>\n" );
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document.write( "go back to d + y = f and replace d with 29 and f = 54 to get:<BR>\n" );
document.write( "29 + y = 54<BR>\n" );
document.write( "solve for y to get y = 54 - 29 = 25\r<BR>\n" );
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document.write( "25 years from now, the daughter will be 29 + 25 = 54<BR>\n" );
document.write( "29 years from now, the father will be 54 + 25 = 79\r<BR>\n" );
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document.write( "the second 2 equations of:\r<BR>\n" );
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document.write( "d + y = f<BR>\n" );
document.write( "f + y = 79\r<BR>\n" );
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document.write( "hold true when d = 29 and f = 54 and y = 25\r<BR>\n" );
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document.write( "29 + 25 = 54 which is the age her father is now.<BR>\n" );
document.write( "54 + 25 = 79 which is the age her father will be when she is as old as her father is now.\r<BR>\n" );
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document.write( "your solution is that the father is 54 and the daughter is 29.\r<BR>\n" );
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document.write( "25 years ago, he was 29 and she was 4.\r<BR>\n" );
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document.write( "25 years from now, he will be 79 and she will be 54.\r<BR>\n" );
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document.write( " </SPAN>\n" );
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