document.write( "Question 134895: A child is 1/3 the age of an older sibling. The sum of the children's ages is 16. How old is the younger child? \n" ); document.write( "
Algebra.Com's Answer #98751 by dbashant(7)\"\" \"About 
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First write an equation that describes the relationship between the children's ages. \r
\n" ); document.write( "\n" ); document.write( "child's age = 1/3 sibling's age
\n" ); document.write( "Let's use C for child's age
\n" ); document.write( "and S for sibling's age.\r
\n" ); document.write( "\n" ); document.write( "So, we have C = 1/3 S\r
\n" ); document.write( "\n" ); document.write( "Next, we know the sum of the ages is 16. So, C + S = 16.\r
\n" ); document.write( "\n" ); document.write( "Now that we have 2 equations with 2 unknowns, C and S, we can solve.\r
\n" ); document.write( "\n" ); document.write( "If we use substituion, we can put 1/3 S from the first equation in place of C in the second equation.\r
\n" ); document.write( "\n" ); document.write( "(1/3 S) + S = 16 Then multiply through by 3 to get rid of the fraction.
\n" ); document.write( "S + 3S = 48 Then simplify
\n" ); document.write( "4S = 48 Then divide by 4 to solve for S.
\n" ); document.write( "S = 12
\n" ); document.write( "Now that we know S = 12, it is easy to solve for C.\r
\n" ); document.write( "\n" ); document.write( "Your answer should give the age of the younger child.
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