document.write( "Question 809810: last year Groks mother weighed 3 times as much as grok. Since then grok has gained 9kg and his mother has lost 4kg. Now his mother weighs only twice as much as Grok. Find their weights \n" ); document.write( "

Algebra.Com's Answer #487829 by josmiceli(19441) $\"\"$ $\"About$

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Let $\"+g+\"$ = Grok's weight now
\n" ); document.write( "Let $\"+m+\"$ = Mother's weight now
\n" ); document.write( "-----------------------------
\n" ); document.write( "(1) $\"+m+=+2g+\"$ kg
\n" ); document.write( "----------------
\n" ); document.write( "Last year, Mother's weight was $\"+m+%2B+4+\"$ kg
\n" ); document.write( "Last year, Grok's weight was $\"+g+-+9+\"$ kg
\n" ); document.write( "---------------
\n" ); document.write( "(2) $\"+m+%2B+4+=+3%2A%28+g+-+9+%29+\"$ kg
\n" ); document.write( "--------------------------
\n" ); document.write( "Substitute (1) into (2)
\n" ); document.write( "(2) $\"+2g+%2B+4+=+3%2A%28+g+-+9+%29+\"$ kg
\n" ); document.write( "(2) $\"+2g+%2B+4+=+3g+-+27+\"$ kg
\n" ); document.write( "(2) $\"+g+=+4+%2B+27+\"$
\n" ); document.write( "(2) $\"+g+=+31+\"$
\n" ); document.write( "and, since
\n" ); document.write( "(1) $\"+m+=+2g+\"$ kg
\n" ); document.write( "(1) $\"+m+=+62+\"$ kg
\n" ); document.write( "Mother is 62 and Grok is 31
\n" ); document.write( "check:
\n" ); document.write( "(2) $\"+m+%2B+4+=+3%2A%28+g+-+9+%29+\"$ kg
\n" ); document.write( "(2) $\"+62+%2B+4+=+3%2A%28+31+-+9+%29+\"$
\n" ); document.write( "(2) $\"+66+=+3%2A22+\"$
\n" ); document.write( "(2) $\"+66+=+66+\"$
\n" ); document.write( "OK \n" ); document.write( "

\n" );