document.write( "Question 514201: Barry is 8 years older than his sister in three years he will be twice as old as she is then. How old are they? \n" ); document.write( "

Algebra.Com's Answer #344093 by Maths68(1474) $\"\"$ $\"About$

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Let
\n" ); document.write( "Present age of Barry = b
\n" ); document.write( "Present age of Sister = s
\n" ); document.write( "Barry is 8 years older than his sister
\n" ); document.write( "b=s+8........(1)
\n" ); document.write( "In three years
\n" ); document.write( "b+3=s+3
\n" ); document.write( "He will be twice as old as his son
\n" ); document.write( "b+3=2(s+3)
\n" ); document.write( "b+3=2s+6
\n" ); document.write( "b=2s+6-3
\n" ); document.write( "b=2s+3
\n" ); document.write( "Subtitute the value of m from (1) to (2)
\n" ); document.write( "s+8=2s+3
\n" ); document.write( "s=2s+3-8
\n" ); document.write( "s-2s=-5
\n" ); document.write( "-s=-5
\n" ); document.write( "Multiply by (-1) both sides
\n" ); document.write( "(-1)(-b)=(-1)(-5)
\n" ); document.write( "s=5
\n" ); document.write( "Put the value of b in (1)
\n" ); document.write( "b=s+8
\n" ); document.write( "b=5+8
\n" ); document.write( "b=13
\n" ); document.write( "Present age of Barry = b = 13
\n" ); document.write( "Present age of Sister = s = 5 \n" ); document.write( "

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