document.write( "Question 1018976: Five years ago, David is 4 times as old as Anna. The present sum of their ages is 25. What are these ages? \n" ); document.write( "

Algebra.Com's Answer #634949 by ikleyn(52781) $\"\"$ $\"About$

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\n" ); document.write( "Five years ago, David $\"highlight%28cross%28is%29%29\"$ was 4 times as old as Anna. The present sum of their ages is 25. What are $\"highlight%28cross%28these%29%29\"$ their ages?
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document.write( "Let D = David's present age, A = Anna's present age.\r\n" );
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document.write( "Five years ago David's age was D-5, while Anna's age was A-5, \r\n" );
document.write( "and the condition says that\r\n" );
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document.write( "D-5 = 4*(A-5).\r\n" );
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document.write( "This is your first equation.\r\n" );
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document.write( "The second is\r\n" );
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document.write( "D + A = 25.\r\n" );
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document.write( "Now express D = 25 - A from the second equation and substitute it into the first. You will get\r\n" );
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document.write( "(25-A) - 5 = 4*(A-5).\r\n" );
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document.write( "Simplify and solve it:\r\n" );
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document.write( "30 - A = 4A - 20,\r\n" );
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document.write( "20 + 20 = 4A + A,\r\n" );
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document.write( "5A = 40,\r\n" );
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document.write( "A =  = 8. \r\n" );
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document.write( "Thus Anna is 8 years now. \r\n" );
document.write( "Hence, David is D = 25 - A = 25 - 8 = 17 years now.\r\n" );
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