document.write( "Question 1129966: Jack is nine years older than Tina. Jack is four times as old as Ali was three year ago. Ali is eighteen years younger than Jack. how old is tina \n" ); document.write( "

Algebra.Com's Answer #746593 by josmiceli(19441) $\"\"$ $\"About$

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Let $\"+a+\"$ = Jack's age now
\n" ); document.write( "Let $\"+b+\"$ = Tina's age now
\n" ); document.write( "Let $\"+c+\"$ = Ali's age now
\n" ); document.write( "----------------------------------
\n" ); document.write( "(1) $\"+a+=+b+%2B+9+\"$
\n" ); document.write( "(2) $\"+a+=+4%2A%28+c+-+3+%29+\"$
\n" ); document.write( "(3) $\"+c+=+a+-+18+\"$
\n" ); document.write( "--------------------------
\n" ); document.write( "Substitute (3) into (2)
\n" ); document.write( "(2) $\"+a+=+4%2A%28+a+-+18+-+3+%29+\"$
\n" ); document.write( "(2) $\"+a+=+4a+-+84+\"$
\n" ); document.write( "(2) $\"+3a+=+84+\"$
\n" ); document.write( "(2) $\"+a+=+28+\"$
\n" ); document.write( "and
\n" ); document.write( "(3) $\"+c+=+28+-+18+\"$
\n" ); document.write( "(3) $\"+c+=+10+\"$
\n" ); document.write( "and
\n" ); document.write( "(1) $\"+28+=+b+%2B+9+\"$
\n" ); document.write( "(1) $\"+b+=+19+\"$
\n" ); document.write( "------------------------
\n" ); document.write( "Tina is 19
\n" ); document.write( "------------------------
\n" ); document.write( "check:
\n" ); document.write( "(2) $\"+a+=+4%2A%28+c+-+3+%29+\"$
\n" ); document.write( "(2) $\"+28+=+4%2A%28+10+-+3+%29+\"$
\n" ); document.write( "(2) $\"+28+=+4%2A7+\"$
\n" ); document.write( "(2) $\"+28+=+28+\"$
\n" ); document.write( "and
\n" ); document.write( "(3) $\"+c+=+a+-+18+\"$
\n" ); document.write( "(3) $\"+10+=+28+-+18+\"$
\n" ); document.write( "(3) $\"+10+=+10+\"$
\n" ); document.write( "and
\n" ); document.write( "(1) $\"+a+=+b+%2B+9+\"$
\n" ); document.write( "(1) $\"+28+=+19+%2B+9+\"$
\n" ); document.write( "(1) $\"+28+=+28+\"$
\n" ); document.write( "OK \n" ); document.write( "

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