document.write( "Question 1142250: 5 years ago Christine's age was 5 times Dave's. In 40 years, Dave will be 15 years more than half Christine's age. How old are they now? \n" ); document.write( "

Algebra.Com's Answer #762943 by ikleyn(52810) $\"\"$ $\"About$

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document.write( "Let D be the Dave age and C be the Christine's age.\r\n" );
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document.write( "Then you have these two equations\r\n" );
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document.write( "    C-5 = 5*(D-5)             (1)      (\"5 years ago Christine's age was 5 times Dave's)\r\n" );
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document.write( "    D + 40 = 15 +       (2)     (\"In 40 years, Dave will be 15 years more than half Christine's age\")\r\n" );
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document.write( "Multiply equation (2) by 2 (both sides).  You will get\r\n" );
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document.write( "    2D + 80 = 30 + C + 40.    (3)\r\n" );
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document.write( "Next express  C = 5*(D-5) + 5 from equation (1) and substitute it into equation (3). You will get\r\n" );
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document.write( "    2D + 80 = 30 + (5*(D-5) + 5) + 40.\r\n" );
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document.write( "Simplify and solve for D.\r\n" );
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document.write( "    2D + 80 = 30 + 5D - 25 + 5 + 40\r\n" );
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document.write( "    2D + 80 = 5D + 50\r\n" );
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document.write( "    80 - 50 = 5D - 2D\r\n" );
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document.write( "    30      = 3D\r\n" );
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document.write( "    D       = 30/3 = 10.\r\n" );
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document.write( "ANSWER.  Dave is 10 years old.  Christine is  C = 5*(D-5) + 5 = 5*(10-5) + 5 = 5*5 + 5 = 30 years old.\r\n" );
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\n" ); document.write( "\n" ); document.write( "You may check it ON YOUR OWN that my answer is correct.\r
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\n" ); document.write( "\n" ); document.write( "There is a bunch of lessons on age word problems \r
\n" ); document.write( "\n" ); document.write( "    - Age problems and their solutions\r
\n" ); document.write( "\n" ); document.write( "    - A fresh formulation of a traditional age problem\r
\n" ); document.write( "\n" ); document.write( "    - Really intricate age word problem\r
\n" ); document.write( "\n" ); document.write( "    - Selected age word problems from the archive\r
\n" ); document.write( "\n" ); document.write( "    - Age problems for mental solution \r
\n" ); document.write( "\n" ); document.write( "    - One unusual age word problem \r
\n" ); document.write( "\n" ); document.write( "    - Age problems with a defective sum of ages \r
\n" ); document.write( "\n" ); document.write( "in this site.\r
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\n" ); document.write( "\n" ); document.write( "Read them and become an expert in solving age problems.\r
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\n" ); document.write( "\n" ); document.write( "Also, you have this free of charge online textbook in ALGEBRA-I in this site\r
\n" ); document.write( "\n" ); document.write( "    - ALGEBRA-I - YOUR ONLINE TEXTBOOK.\r
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\n" ); document.write( "\n" ); document.write( "The referred lessons are the part of this online textbook under the topic \"Age word problems\".\r
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\n" ); document.write( "\n" ); document.write( "Save the link to this online textbook together with its description\r
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\n" ); document.write( "\n" ); document.write( "Free of charge online textbook in ALGEBRA-I
\n" ); document.write( "https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson\r
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\n" ); document.write( "\n" ); document.write( "to your archive and use it when it is needed.\r
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