document.write( "Question 993937: Four years ago, Jane was twice as old as Sam. Four years on from now, Sam will be ž of Jane's age. How old is Jane now? \n" ); document.write( "

Algebra.Com's Answer #613094 by josmiceli(19441) $\"\"$ $\"About$

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Let $\"+j+\"$ = Jane's age now
\n" ); document.write( "Let $\"+s+\"$ = Sam's age now
\n" ); document.write( "(1) $\"+j+-+4+=+2%2A%28+s+-+4+%29+\"$
\n" ); document.write( "(2) $\"+s+%2B+4+=+%283%2F4%29%2A%28+j+%2B+4+%29+\"$
\n" ); document.write( "-------------------------
\n" ); document.write( "(1) $\"+j+-+4+=+2s+-+8+\"$
\n" ); document.write( "(1) $\"+2s+-+j+=+4+\"$
\n" ); document.write( "-------------------
\n" ); document.write( "(2) $\"+4s+%2B+16+=+3j+%2B+12+\"$
\n" ); document.write( "(2) $\"+-4s+%2B+3j+=+4+\"$
\n" ); document.write( "----------------------
\n" ); document.write( "Multiply both sides of (1) by $\"+3+\"$
\n" ); document.write( "and add the equations
\n" ); document.write( "(1) $\"+6s+-+3j+=+12+\"$
\n" ); document.write( "(2) $\"+-4s+%2B+3j+=+4+\"$
\n" ); document.write( "--------------------
\n" ); document.write( " $\"+2s+=+16+\"$
\n" ); document.write( " $\"+s+=+8+\"$
\n" ); document.write( "and
\n" ); document.write( "(1) $\"+j+-+4+=+2%2A%28+8+-+4+%29+\"$
\n" ); document.write( "(1) $\"+j+=+2%2A4+%2B+4+\"$
\n" ); document.write( "(1) $\"+j+=+12+\"$
\n" ); document.write( "Jane is 12 now
\n" ); document.write( "---------------
\n" ); document.write( "check:
\n" ); document.write( "4 yrs ago, Jane was 8
\n" ); document.write( "4 yrs ago, Sam was 4
\n" ); document.write( "Jane was 2X as old
\n" ); document.write( "------------------
\n" ); document.write( "In 4 yrs, Sam is 12
\n" ); document.write( "In 4 yrs, Jane is 16
\n" ); document.write( " $\"+%283%2F4%29%2A16+=+12+\"$
\n" ); document.write( "OK \n" ); document.write( "

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