document.write( "Question 608465: 3 YEARS AGO THE RATIO OF THE AGE OF A FATHER AND HIS DAUGHTER WAS 4:1. AFTER 5 YEARS THE RATIO WILL BE 8:3. FIND THEIR PRESENT AGES. \n" ); document.write( "
Algebra.Com's Answer #383240 by Edwin McCravy(20056)\"\" \"About 
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3 YEARS AGO THE RATIO OF THE AGE OF A FATHER AND HIS DAUGHTER
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document.write( "(F-3):(D-3) = 4:1\r\n" );
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document.write( "(F+5):(D+5) = 8:3\r\n" );
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document.write( "The system of equations is\r\n" );
document.write( "\"system%28%28F-3%29%2F%28D-3%29+=+4%2F1%2C%0D%0A%28F%2B5%29%2F%28D%2B5%29+=+8%2F3%29\"\r\n" );
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document.write( "Cross-multiply both equations:\r\n" );
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document.write( "\"system%28F-3+=+4%28D-3%29%2C%0D%0A3%28F%2B5%29+=+8%28D%2B5%29%29\"\r\n" );
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document.write( "Distribute:\r\n" );
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document.write( "\"system%28F-3+=+4D+-+12%2C%0D%0A3F+%2B+15+=+8D+%2B+40%29\"\r\n" );
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document.write( "\"system%28F-4D=+-9%2C%0D%0A3F-8D+=+25%29\"\r\n" );
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document.write( "Solve by substitution.\r\n" );
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document.write( "Solve the first equation for F\r\n" );
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document.write( "F = 4D - 9\r\n" );
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document.write( "Substitute (4D - 9) for F in the second\r\n" );
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document.write( "3(4D - 9) - 8D = 25\r\n" );
document.write( " 12D - 27 - 8D = 25\r\n" );
document.write( "            4D = 52\r\n" );
document.write( "             D = 13\r\n" );
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document.write( "Substitute (13) for D in\r\n" );
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document.write( "F = 4D - 9\r\n" );
document.write( "F = 4(13) - 9\r\n" );
document.write( "F = 52 - 9\r\n" );
document.write( "F = 43.\r\n" );
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document.write( "The father is 43 and the daughter is 13.\r\n" );
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document.write( "Checking with the words:\r\n" );
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document.write( "3 YEARS AGO THE RATIO OF THE AGE OF A FATHER was \r\n" );
document.write( "43-3 or 40 AND HIS DAUGHTER WAS 13-3 or 10 and \r\n" );
document.write( "40:10 is in the ratio of 4:1 (dividing 40 and 10 \r\n" );
document.write( "both by 10).\r\n" );
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document.write( "AFTER 5 YEARS THE father will be 43+5 or 48 and \r\n" );
document.write( "the daughter will be 13+5 or 18 and 48:18 is in \r\n" );
document.write( "the ratio of  8:3 (dividing 48 and 18 both by 6).\r\n" );
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document.write( "Edwin
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