document.write( "Question 230629: John is twice as old as his brother. Four years ago, he was four times as old as his brother. Find their present ages. \n" ); document.write( "

Algebra.Com's Answer #170929 by ankor@dixie-net.com(22740) $\"\"$ $\"About$

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Let j = John's present age
\n" ); document.write( "Let b = brother's age now
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\n" ); document.write( "John is twice as old as his brother.
\n" ); document.write( "j = 2b
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\n" ); document.write( " Four years ago, he was four times as old as his brother.
\n" ); document.write( "j - 4 = 4(b - 4)
\n" ); document.write( "j - 4 = 4b - 16
\n" ); document.write( "j = 4b - 16 + 4
\n" ); document.write( "j = 4b - 12
\n" ); document.write( ":
\n" ); document.write( " Find their present ages.
\n" ); document.write( "Replace j with 2b in the above equation
\n" ); document.write( "2b = 4b - 12
\n" ); document.write( "12 = 4b - 2b
\n" ); document.write( "12 = 2b
\n" ); document.write( "b = 6 yrs is bro
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\n" ); document.write( "obviously, John is 12,
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\n" ); document.write( "Prove this in the statement:
\n" ); document.write( "\"Four years ago, he was four times as old as his brother. \"
\n" ); document.write( "12 - 4 = 4(6 - 4)
\n" ); document.write( "8 = 4(2) \n" ); document.write( "

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