document.write( "Question 443188: Max is four times older than his sister.
\n" ); document.write( "she is 9 years younger than max.
\n" ); document.write( "how old is max? \n" ); document.write( "

Algebra.Com's Answer #305716 by josmiceli(19441) $\"\"$ $\"About$

You can put this solution on YOUR website!
Let $\"s\"$ = Sister's age
\n" ); document.write( "Let $\"m\"$ = Max's age
\n" ); document.write( "given:
\n" ); document.write( " $\"+m+=+4s+\"$
\n" ); document.write( " $\"+s+=+m+-+9+\"$
\n" ); document.write( "By substitution,
\n" ); document.write( " $\"+m+=+4%2A%28m+-+9%29+\"$
\n" ); document.write( " $\"+m+=+4m+-+36+\"$
\n" ); document.write( " $\"+3m+=+36+\"$
\n" ); document.write( " $\"+m+=+12+\"$
\n" ); document.write( "Max is 12
\n" ); document.write( "check:
\n" ); document.write( " $\"+s+=+m+-+9+\"$
\n" ); document.write( " $\"+s+=+3+\"$
\n" ); document.write( "and
\n" ); document.write( " $\"+m+=+4s+\"$
\n" ); document.write( " $\"+m+=+4%2A3+\"$
\n" ); document.write( " $\"+m+=+12+\"$
\n" ); document.write( "OK \n" ); document.write( "

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