document.write( "Question 1111879: Mrs. Chen was 20 when her eldest child was born. Two years later, another child was born and four years after that, her youngest child was born. Now the averages of their four ages are 39. How old are Mrs. Chen and her three children now? \r
\n" ); document.write( "\n" ); document.write( "It would be great if an equation was written out first, thanks. \n" ); document.write( "

Algebra.Com's Answer #726944 by josmiceli(19441) $\"\"$ $\"About$

You can put this solution on YOUR website!
Let $\"+a+\"$ = Mrs. Chen's age now.
\n" ); document.write( "Let $\"+b+\"$ = age of eldest child now
\n" ); document.write( "Let $\"+c+\"$ = age of middle child now
\n" ); document.write( "Let $\"+d+\"$ = age of youngest child now
\n" ); document.write( "--------------------------------------
\n" ); document.write( "(1) $\"+a+-+b+=+20+\"$
\n" ); document.write( "( the difference in their ages will always be 20 yrs )
\n" ); document.write( "(2) $\"+a+-+c+=+22+\"$
\n" ); document.write( "(3) $\"+a+-+d+=+26+\"$
\n" ); document.write( "(4) $\"+%28+a+%2B+b+%2B+c+%2B+d+%29+%2F+4+=+39+\"$
\n" ); document.write( "---------------------------------
\n" ); document.write( "(1) $\"+b+=+a+-+20+\"$
\n" ); document.write( "(2) $\"+c+=+a+-+22+\"$
\n" ); document.write( "(3) $\"+d+=+a+-+26+\"$
\n" ); document.write( "By substitution:
\n" ); document.write( "(4) $\"+%28+a+%2B+a+-+20+%2B+a+-+22+%2B+a+-+26+%29+%2F+4+=+39+\"$
\n" ); document.write( "(4) $\"+4a+-+68+%29+%2F+4+=+39+\"$
\n" ); document.write( "(4) $\"+4a+-+68+=+156+\"$
\n" ); document.write( "(4) $\"+4a+=+224+\"$
\n" ); document.write( "(4) $\"+a+=+56+\"$
\n" ); document.write( "and
\n" ); document.write( "(1) $\"+b+=+a+-+20+\"$
\n" ); document.write( "(1) $\"+b+=+56+-+20+\"$
\n" ); document.write( "(1) $\"+b+=+36+\"$
\n" ); document.write( "and
\n" ); document.write( "(2) $\"+c+=+a+-+22+\"$
\n" ); document.write( "(2) $\"+c+=+56+-+22+\"$
\n" ); document.write( "(2) $\"+c+=+34+\"$
\n" ); document.write( "and
\n" ); document.write( "(3) $\"+d+=+a+-+26+\"$
\n" ); document.write( "(3) $\"+d+=+56+-+26+\"$
\n" ); document.write( "(3) $\"+d+=+30+\"$
\n" ); document.write( "--------------------------
\n" ); document.write( "Their ages are:
\n" ); document.write( "56, 36, 34, and 30
\n" ); document.write( "---------------------------
\n" ); document.write( "check:
\n" ); document.write( " $\"+%28+a+%2B+b+%2B+c+%2B+d+%29+%2F+4+=+39+\"$
\n" ); document.write( " $\"+%28+56+%2B+36+%2B+34+%2B+30+%29+%2F+4+=+39+\"$
\n" ); document.write( " $\"+156%2F4+=+39+\"$
\n" ); document.write( " $\"+156+=+156+\"$
\n" ); document.write( "OK
\n" ); document.write( " \n" ); document.write( "

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